VARIATIONS IN THE COLOR OF FISHES

The Oniokose or Demon Stinger, Inimicus japonicus (Cuv. and Val.), from Wakanoura, Japan. From nature by Kako Morita.

Surface coloration about lava rocks.

Coloration of specimens living among red algæ.

Coloration in deep water; Inimicus aurantiacus (Schlegel).

The adoption of the Code of the International Congress of Zoology necessitates a few changes in generic names used in this book.

Subclass Actinopteri.—In our glance over the taxonomy of the earlier Chordates, or fish-like vertebrates, we have detached from the main stem one after another a long series of archaic or primitive types. We have first set off those with rudimentary notochord, then those with retrogressive development who lose the notochord, then those without skull or brain, then those without limbs or lower jaw. The residue assume the fish-like form of body, but still show great differences among themselves. We have then detached those without membrane-bones, or trace of lung or air-bladder. We next part company with those having the air-bladder a veritable lung, and those with an ancient type of paired fins, a jointed axis fringed with rays, and those having the palate still forming the upper jaw. We have finally left only those having fish-jaws, fish-fins, and in general the structure of the modern fish. For all these in all their variety, as a class or subclass, the name Actinopteri, or Actinopterygii, suggested by Professor Cope, is now generally adopted. The shorter form, Actinopteri, being equally correct is certainly preferable. This term (ακτίς, ray; πτερόν or πτερύξ, fin) refers to the structure of the paired fins. In all these fishes the bones supporting the fin-rays are highly specialized and at the same time concealed by the general integument of the body. In general two bones connect the pectoral fin with the shoulder-girdle. The hypercoracoid is a flat square bone, usually perforated by a foramen. Lying below it and parallel with it is the irregularly formed hypocoracoid. Attached to them is a row of bones, the actinosts, or pterygials, short, often hour-glass-shaped, which actually support the fin-rays. In the more specialized forms, or Teleosts, the actinosts are few (four to six) in number, 2but in the more primitive types, or Ganoids, they may remain numerous, a reminiscence of the condition seen in the Crossopterygians, and especially in Polypterus. Other variations may occur; the two coracoids sometimes are imperfect or specially modified, the upper sometimes without a foramen, and the actinosts may be distorted in form or position.

Fig. 1.—Shoulder-girdle of a Flounder, Paralichthys californicus (Ayres).

The Series Ganoidei.—Among the lower Actinopteri many archaic traits still persist, and in its earlier representatives the group approaches closely to the Crossopterygii, although no forms actually intermediate are known either living or fossil. The great group of Actinopteri may be divided into two series or subclasses, the Ganoidei, or Chrondrostei, containing those forms, mostly extinct, which retain archaic traits of one sort or another, and the Teleostei, or bony fishes, in which most of the primitive characters have disappeared. Doubtless all of the Teleostei are descended from a ganoid ancestry.

Even among the Ganoidei, as the term is here restricted, there remains a very great variety of form and structure. The fossil and existing forms do not form continuous series, but represent the tips and remains of many diverging branches perhaps from some Crossopterygian central stock. The group constitutes at least three distinct orders and, as a whole, does not admit of 3perfect definition. In most but not all of the species the tail is distinctly and obviously heterocercal, the lack of symmetry of the tail in some Teleosts being confined to the bones and not evident without dissection. Most of the Ganoids have the skeleton still cartilaginous, and in some it remains in a very primitive condition. Usually the Ganoids have an armature of bony plates, diamond-shaped, with an enamel like that developed on the teeth. In all of them the pectoral fin has numerous basal bones or actinosts. All of them have the air-bladder highly developed, usually cellular and functional as a lung, but connecting with the dorsal side of the gullet, not with the ventral side as in the Dipnoans. In all living forms there is a more or less perfect optic chiasma. These ancient forms retain also the many valves of the arterial bulb and the spiral valve of the intestines found in the more archaic types of fishes. But traces of some or all of these structures are found in some bony fishes, and their presence in the Ganoids by no means justifies the union of the Ganoids with the sharks, Dipnoans, and Crossopterygians to form a great primary class, Palæichthyes, as proposed by Dr. Günther. Almost every form of body may be found among the Ganoids. In the Mesozoic seas these fishes were scarcely less varied and perhaps scarcely less abundant than the Teleosts in the seas of to-day. They far exceed the Crossopterygians in number and variety of forms. Transitional forms connecting the two groups are thus far not recognized. So far as fossils show, the characteristic actinopterous fin with its reduced and altered basal bones appeared at once without intervening gradations.

The name Ganoidei (γάνος, brightness; εἶδος, resemblance), alluding to the enameled plates, was first given by Agassiz to those forms, mostly extinct, which were covered with bony scales or hard plates of one sort or another. As the term was originally defined, mailed catfishes, sea-horses, Agonidæ, Arthrodires, Ostracophores, and other wholly unrelated types were included with the garpikes and sturgeons as Ganoids. Most of these intruding forms among living fishes were eliminated by Johannes Müller, who recognized the various archaic characters common to the existing forms after the removal of the mailed Teleosts. Still later Huxley separated the Crossopterygians as a distinct 4group, while others have shown that the Ostracophori and Arthrodira should be placed far from the garpike in systematic classification. Cope, Woodward, Hay, and others have dropped the name Ganoid altogether as productive of confusion through the many meanings attached to it. Others have kept it as a convenient group name for the orders of archaic Actinopteri. For these varied and more or less divergent forms it seems convenient to retain it. As an adjective "ganoid" is sometimes used as descriptive of bony plates or enameled scales, some-in the sense of archaic, as applied to fishes.

Are the Ganoids a Natural Group?—Several writers have urged that the Ganoidei, even as thus restricted, should not be considered as a natural group, whether subclass, order, or group of orders. The reasons for this view in brief are the following:

1. The group is heterogeneous. The Amiidæ differ more from the other Ganoids than they do from the herring-like Teleosts. The garpikes, sturgeons, paddle-fishes likewise diverge widely from each other and from the Palæoniscidæ and the Platysomidæ. Each of the living families represents the residue or culmination of a long series, in some cases advancing, as in the case of the bowfin, sometimes perhaps degenerating, as in the case of the sturgeons.

2. Of the traits possessed in common by these forms, several (the cellular air-bladder, the many valves in the heart, the spiral valve in the intestine, the heterocercal tail) are all possessed in greater or less degree by certain Isospondyli or allies of the herring. All these characters are still better developed in Crossoptergyii and Dipneusti, and each one disappears by degrees. Of the characters drawn from the soft parts we can know nothing so far as the extinct Ganoids are concerned.

3. The optic chiasma, thus far characteristic of Ganoids as distinct from Teleosts, may have no great value. It is urged that in closely related species of lizards some have the optic chiasma and others do not. This, however, proves nothing as to the value of the same character among fishes.

4. The transition from Ganoids to Teleosts is of much the same character as the transition from spiny-rayed to soft-rayed fishes, or that from fishes with a duct to the air-bladder to those without such duct.

5Admitting all this, it is nevertheless natural and convenient to retain the Ganoidei (or Chrondrostei if the older name be discarded on account of the many meanings attached to it) as a group equivalent to that of Teleostei within the class or subclass of Actinopteri. It comprises the transitional forms between the Crossopterygii and the bony fishes, and its members are especially characteristic of the Mesozoic age, ranging from the Devonian to the present era.

Of the extensive discussion relating to this important question we may quote two arguments for the retention of the subclass of Ganoids, the first by Francis M. Balfour and William Kitchen Parker, the second from the pen of Theodore Gill.

Balfour and Parker ("Structure and Development of Lepidosteus," pp. 430-433) thus discuss the

Systematic Position of Lepidosteus.—"Alexander Agassiz concludes his memoir on the development of Lepidosteus by pointing out that in spite of certain affinities in other directions this form is 'not so far removed from the bony fishes as has been supposed.' Our own observations go far to confirm Agassiz's opinion.

"Apart from the complete segmentation, the general development of Lepidosteus is strikingly Teleostean. In addition to the general Teleostean features of the embryo and larva, which can only be appreciated by those who have had an opportunity of practically working at the subject, we may point to the following developmental features^[2] as indicative of Teleostean affinities:

"(1) The formation of the nervous system as a solid keel of the epiblast.

"(2) The division of the epiblast into a nervous and epidermic stratum.

"(3) The mode of development of the gut.

"(4) The mode of development of the pronephros; though the pronephros of Lepidosteus has primitive characters not retained by Teleostei.

"(5) The early stages in the development of the vertebral column.

6"In addition to these, so to speak, purely embryonic characters there are not a few important adult characters:

"(1) The continuity of the oviducts with the genital glands.

"(2) The small size of the pancreas, and the presence of numerous so-called pancreatic cæca.

"(3) The somewhat coiled small intestine.

"(4) Certain characters of the brain, e.g., the large size of the cerebellum; the presence of the so-called lobi inferiores on the infundibulum, and of tori semi-circulares in the mid-brain.

"In spite of the undoubtedly important list of features to which we have just called attention, a list containing not less important characters, both embryological and adult, separating Lepidosteus from the Teleostei, can be drawn up:

"(1) The character of the truncus arteriosus.

"(2) The fact of the genital ducts joining the ureters.

"(3) The presence of vasa efferentia in the male carrying the semen from the testes to the kidney, and through the tubules of the latter into the kidney-duct.

"(4) The presence of a well-developed opercular gill.

"(5) The presence of a spiral valve; though this character may possibly break down with the extension of our knowledge.

"(6) The typical Ganoid characters of the thalamencephalon and the cerebral hemispheres.

"(7) The chiasma of the optic nerves.

"(8) The absence of a pecten, and presence of a vascular membrane between the vitreous humor and the retina.

"(9) The opisthocœlous form of the vertebræ.

"(10) The articulation of the ventral parts of the hæmal arches of the tail with the processes of the vertebral column.

"(11) The absence of a division of the muscles into dorso-lateral and ventro-lateral divisions.

"(12) The complete segmentation of the ovum.

"The list just given appears to us sufficient to demonstrate that Lepidosteus cannot be classed with the Teleostei; and we hold that Müller's view is correct, according to which Lepidosteus is a true Ganoid.

"The existence of the Ganoids as a distinct group has, however, recently been challenged by so distinguished an ichthyologist 7as Günther, and it may therefore be well to consider how far the group as defined by Müller is a natural one for living forms, and how far recent researches enable us to improve upon Müller's definitions. In his classical memoir the characters of the Ganoids are thus shortly stated:

"'These fishes are either provided with plate-like angular or rounded cement-covered scales, or they bear osseous plates, or are quite naked. The fins are often, but not always, beset with a double or single row of spinous plates or splints. The caudal fin embraces occasionally in its upper lobe the end of the vertebral column, which may be prolonged to the end of the upper lobe. Their double nasal openings resemble those of Teleostei. The gills are free, and lie in a branchial cavity under an operculum, like those of Teleostei. Many of them have an accessory organ of respiration, in the form of an opercular gill, which is distinct from the pseudobranch, and can be present together with the latter; many also have spiracles like Elasmobranchii. They have many valves in the stem of the aorta like the latter, also a muscular coat in the stem of the aorta. Their ova are transported from the abdominal cavity by oviducts. Their optic nerves do not cross each other. The intestine is often provided with a spiral valve, like Elasmobranchii. They have a swimming-bladder with a duct, like many Teleostei. Their pelvic fins are abdominal.

"'If we include in a definition only those characters which are invariable, the Ganoids may be shortly defined as being those fish with numerous valves to the stem of the aorta, which is also provided with a muscular coat, with free gills, and an operculum, and with abdominal pelvic fins.'

"To these distinctive characters he adds, in an appendix to his paper, the presence of the spiral valve, and the absence of a processus falciformis and a choroid gland.

"To the distinctive set of characters given by Müller we may probably add the following:

"(1) Oviducts and urinary ducts always unite, and open by a common urogenital aperture behind the anus.

"(2) Skull hyostylic.

"(3) Segmentation complete in the types so far investigated, 8though perhaps Amia may be found to resemble the Teleostei in this particular.

"(4) A pronephros of the Teleostean type present in the larva.

"(5) Thalamencephalon very large and well developed.

"(6) The ventricle in the posterior part of the cerebrum is not divided behind into lateral halves, the roof of the undivided part being extremely thin.

"(7) Abdominal pores always present.

"The great number of characters just given are amply sufficient to differentiate the Ganoids as a group; but, curiously enough, the only characters, amongst the whole series which have been given, which can be regarded as peculiar to the Ganoids are (1) the characters of the brain, and (2) the fact of the oviducts and kidney-ducts uniting together and opening by a common pore to the exterior.

"This absence of characters peculiar to the Ganoids is an indication of how widely separated in organization are the different members of this great group.

"At the same time, the only group with which existing Ganoids have close affinities is the Teleostei. The points they have in common with the Elasmobranchii are merely such as are due to the fact that both retain numerous primitive vertebrate characters,^[3] and the gulf which really separates them is very wide.

"There is again no indication of any close affinity between the Dipnoans and, at any rate, existing Ganoids.

"Like the Ganoids, the Dipnoans are no doubt remnants of a very primitive stock; but in the conversion of the air-bladder into a true lung, the highly specialized character of their limbs,^[4] their peculiar autostylic skulls, the fact of their ventral nasal openings leading directly into the mouth, their multi-segmented bars (interspinous bars) directly prolonged from the neural and hæmal and supporting the fin-rays of the unpaired dorsal 9and ventral fins, and their well-developed cerebral hemispheres, very unlike those of Ganoids and approaching the Amphibian type, they form a very well-defined group and one very distinctly separated from the Ganoids.

"No doubt the Chondrostean Ganoids are nearly as far removed from the Teleostei as from the Dipnoans, but the links uniting these Ganoids with the Teleostei have been so fully preserved in the existing fauna of the globe that the two groups almost run into each other. If, in fact, we were anxious to make any radical change in the ordinary classification of fishes, it would be by uniting the Teleostei and Ganoids, or rather constituting the Teleostei into one of the subgroups of the Ganoids, equivalent to the Chondrostei. We do not recommend such an arrangement, which in view of the great preponderance of the Teleostei amongst living fishes would be highly inconvenient, but the step from Amia to the Teleostei is certainly not so great as that from the Chondrostei to Amia, and is undoubtedly less than that from the Selachii to the Holocephali."

Gill on the Ganoids as a Natural Group.—Dr. Gill observes ("Families of Fishes," 1872): "The name Ganoides (or Ganiolepedoti) was originally framed by Prof. Agassiz as an ordinal term for fishes having the scales (when present) angular and covered with enamel; and in the group so characterized were combined the Ganoids of subsequent authors as well as the Teleostean orders Plectognathi, Lophobranchii, and Nematognathi, and (subsequently) the genus Sudis (Arapaima), the last being regarded as a Cœlacanth. The group has not been accepted with these limits or characters.

"But the researches of Prof. Johannes Müller on the anatomy and classification of the fishes culminated at length in his celebrated memoirs on those fishes for which he retained the ordinal name Ganoidei; those memoirs have left an impression on ichthyology perhaps more decided than made by any other contributions to science, and that published in extenso will ever be classical; numerous as have been the modifications since introduced into the system, no forms except those recognized by Müller (unless it be Dipnoi) have been interjected since among the Ganoids.

10"It has been objected that the Ganoids do not constitute a natural group, and that the characters (i.e., chiasma of optic nerves and multivalvular bulbus arteriosus) alleged by Müller to be peculiar to the teleostomous forms combined therein are problematical, and only inferentially supposed to be common to the extinct Ganoids so called, and, finally, such objections couched in too strong language have culminated in the assertion that the characters in question are actually shared by other physostome fishes.

"No demonstration, however, has been presented as yet that any physostome fishes do really have the optic chiasma and multivalvular bulbus arteriosus, and the statement to the contrary seems to have been the result of a venial misapprehension of Prof. Kner's statements, or the offspring of impressions left on the memory by his assertions, in forgetfulness of his exact words.

"But Prof. Kner, in respect to the anatomical characters referred to, merely objects: (1) that they are problematical, are not confirmable for the extinct types, and were probably not existent in certain forms that have been referred to the Ganoids; (2) the difference in number of the valves of the bulbus arteriosus among recent Ganoids is so great as to show the unreliability of the character; (3) a spiral valve is developed in the intestine of several osseous fishes ('genera of the so-called intermediate clupeoid groups'), as well as in Ganoids; and (4) the chiasma of the optic nerves in no wise furnishes a positive character for the Ganoids.

"It will be noticed that all these objections (save in the case of the intestinal spiral valve) are hypothetical and vague. The failure of the intestinal spiral valve, as a diagnostic character, has long been conceded, and in this case only have the forms that prove the failure been referred to; in the other cases, where it would be especially desirable to have indicated the actual types falsifying the universality or exclusiveness of the characters, they have not been referred to, and the objections must be met as if they were not known to exist.

"(1) The characters in question are, in the sense used, problematical, inasmuch as no examination can be made of the soft parts of extinct forms, but with equal force may it be 11urged that any characters that have not been or cannot be directly confirmed are problematical in the case of all other groups (e.g., mammals), and it can only be replied that the coordination of parts has been so invariably verified that all probabilities are in favor of similar coordination in any given case.

"(2) There is doubtless considerable difference in the number of valves of the bulbus arteriosus among the various Ganoids, and even among the species of a single family (e.g., Lepidosteidæ), but the character of Ganoids lies not in the number, more or less, but in the greater number and relations (in contradistinction to the opposite pair of the Teleosts) in conjunction with the development of a bulbus arteriosus. In no other forms of Teleostomes have similar relations and structures been yet demonstrated.

"(3) The failure of the spiral intestinal valve has already been conceded, and no great stress has ever been laid on the character.

"(4) The chiasma of the optic nerves is so common to all the known Ganoids, and has not been found in those forms (e.g., Arapaima, Osteoglossum, and Clupeiform types) agreeing with typical physostome Teleosts in the skeleton, heart, etc., but which at the same time simulate most certain Ganoids (e.g., Amia) in form.

"Therefore, in view of the evidence hitherto obtained, the arguments against the validity of title, to natural association, of the Ganoids, have to meet the positive evidence of the coordinations noted; the value of such characteristics and coordinations can only be affected or destroyed by the demonstration that in all other respects there is (1) very close agreement of certain of the constituents of the subclass with other forms, and (2) inversely proportionate dissimilarity of those forms from any (not all) other of the Ganoids, and consequently evidence ubi plurima nitent against the taxonomic value of the characters employed for distinction.

"And it is true that there is a greater superficial resemblance between the Hyoganoids (Lepisosteus, Amia, etc.) and ordinary physostome Teleosts than between the former and the other orders of Ganoids, but it is equally true that they agree in other respects than in the brain and heart with the more generalized 12Ganoids. They all have, for example, (1) the paraglenal elements undivided (not disintegrated into hypercoracoid, hypocoracoid, and mesocoracoid); (2) a humerus (simple or divided, that is, differentiated into metapterygium and mesopterygium); and (3) those with ossified skeletons agree in the greater number of elements in the lower jaw. Therefore, until these coordinates fail, it seems advisable to recognize the Ganoids as constituents of a natural series; and especially on account of the superior taxonomic value of modifications of the brain and heart in other classes of vertebrates, for the same reason, and to keep prominently before the mind the characters in question, it appears also advisable to designate the series, until further discovery, as a subclass.

"But it is quite possible that among some of the generalized Teleosts at least traces of some of the characters now considered to be peculiar to the Ganoids may be discovered. In anticipation of such a possibility, the author had at first discarded the subclass, recognizing the group only as one of the 'superorders' of the Teleostomes, but reconsideration convinces him of the propriety of classification representing known facts and legitimate inferences rather than too much anticipation.

"It is remembered that all characters are liable to fail with increasing knowledge, and the distinctness of groups are but little more than the expressions of our want of knowledge of the intermediate forms; it may in truth be said that ability to segregate a class into well-defined groups is in ratio to our ignorance of all the terms."

Classification of Ganoids.—The subdivision of the series of Ganoidei into orders offers great difficulty from the fact of the varying relationships of the members of the group and the fact that the great majority of the species are known only from broken skeletons preserved in the rocks. It is apparently easy to separate those with cartilaginous skeletons from those with these bones more or less ossified. It is also easy to separate those with bony scales or plates from those having the scales cycloid. But the one type of skeleton grades into the other, and there is a bony basis even to the thinnest of scales found in this group. Among the multitude of names and divisions proposed we may recognize six orders, for which the names Lysopteri, Chondrostei, Selachostomi, Pycnodonti, Lepidostei, and Halecomorphi are not inappropriate. Each of these seems to represent a distinct offshoot from the first primitive group.

Order Lysopteri.—In the most primitive order, called Lysopteri (λυσός, loose; πτερόν, fin) by Cope, Heterocerci by Zittel and Eastman, and the "ascending series of Chondrostei" by Woodward, we find the nearest approach to the Chondropterygians. In this order the arches of the vertebræ are more or less ossified, the body is more or less short and deep, covered with bony dermal plates. The opercular apparatus is well developed, with numerous branchiostegals. Infraclavicles are present, and the fins provided with fulcra. Dorsal and anal fins are present, with rays more numerous than their supports; ventral fin with basal supports which are imperfectly ossified; caudal fin mostly heterocercal, the scales mostly rhombic in form. All the members of this group are now extinct.

14The Palæoniscidæ.—The numerous genera of this order are referred to three families, the Palæoniscidæ, Platysomidæ, and Dictyopygidæ; a fourth family, Dorypteridæ, of uncertain relations, being also tentatively recognized. The family of Palæoniscidæ is the most primitive, ranging from the Devonian to the Lias, and some of them seem to have entered fresh waters in the time of the coal-measures. These fishes have the body elongate and provided with one short dorsal fin. The tail is heterocercal and the body covered with rhombic plates. Fulcra or rudimentary spine-like scales are developed on the upper edge of the caudal fin in most recent Ganoids, and often the back has a median row of undeveloped scales. A multitude of species and genera are recorded. A typical form is the genus Palæoniscum,^[5] with many species represented in the rocks of various parts of the world. The longest known species is Palæoniscum frieslebenense from the Permian of Germany and England. Palæoniscum magnum, sixteen inches long, occurs in the Permian of Germany. From Canobius, the most primitive genus, to Coccolepis, the most modern, is a continuous series, the suspensorium of the lower jaw becoming more oblique, the basal bones of the dorsal fewer, the dorsal extending farther forward, and the scales more completely imbricate. Other prominent genera are Amblypterus, Eurylepis, Cheirolepis, Rhadinichthys, Pygopterus, Elonichthys, Ærolepis, Gyrolepis, Myriolepis, Oxygnathus, Centrolepis, and Holurus.

Fig. 2.—Palæoniscum frieslebenense Blainville. Family Palæoniscidæ. (After Zittel.)

The Platysomidæ.—The Platysomidæ are different in form, the body being deep and compressed, often diamond-shaped, 15with very long dorsal and anal fins. In other respects they are very similar to the Palæoniscidæ, the osteology being the same. The Palæoniscidæ were rapacious fishes with sharp teeth, the Platysomidæ less active, and, from the blunter teeth, probably feeding on small animals, as crabs and snails.

The rhombic enameled scales are highly specialized and held together as a coat of mail by peg-and-socket joints. The most extreme form is Platysomus, with the body very deep. Platysomus gibbosus and other species occur in the Permian rocks of Germany. Cheirodus is similar to Platysomus, but without ventral fins. Eurynotus, the most primitive genus, is remarkable for its large pectoral fins. Eurynotus crenatus occurs in the Subcarboniferous of Scotland. Other genera are Mesolepis, Globulodus, Wardichthys, and Cheirodopsis.

Fig. 3.—Eurynotus crenatus Agassiz, restored. Carboniferous. Family Platysomidæ. (After Traquair.)

Some of the Platysomidæ have the interneural spines projecting through the skin before the dorsal fin. This condition is found also in certain bony fishes allied to the Carangidæ.

The Dorypteridæ.—Dorypterus hoffmani, the type of the singular Palæozoic family of Dorypteridæ, with thoracic or sub-jugular many-rayed ventrals, is Stromateus-like to all appearance, with distinct resemblances to certain Scombroid forms, but with a heterocercal tail like a ganoid, imperfectly ossified back-bone, and other very archaic characters. The body is apparently scaleless, unlike the true Platysomidæ, in which the 16scales are highly developed. A second species, Dorypterus althausi, also from the German copper shales, has been described. This species has lower fins than Dorypterus hoffmani, but may be the adult of the same type. Dorypterus is regarded by Woodward as a specialized offshoot from the Platysomidæ. The many-rayed ventrals and the general form of the body and fins suggest affinity with the Lampridæ.

Fig. 4.—Dorypterus hoffmani Germar, restored. (After Hancock and Howse.)

Dictyopygidæ.—In the Dictyopygidæ (Catopteridæ), the body is gracefully elongate, less compressed, the heterocercal tail is short and abruptly turned upwards, the teeth are sharp and usually hooked, and the bony plates well developed. Of this group two genera are recognized, each containing numerous species. In Redfieldius (= Catopterus Redfield, not of Agassiz) the dorsal is inserted behind the anal, while in Dictyopyge this is not the case. Redfieldius gracilis and other species are found in the Triassic of the Connecticut River. Dictyopyge macrura is found in the same region, and Dictyopyge catoptera and other species in Europe.

17Order Chondrostei.—The order Chondrostei (χόνδρος, cartilage; ὀστέον, bone), as accepted by Woodward, is characterized by the persistence of the notochord in greater or less degree, the endoskeleton remaining cartilaginous. In all, the axonosts and baseosts of the median fins are arranged in simple regular series and the rays are more numerous than the supporting elements. The shoulder-girdle has a pair of infraclavicular plates. The pelvic fins have well-developed baseosts. The branchiostegals are few or wanting. In the living forms, and probably in all others, a matter which can never be ascertained, the optic nerves are not decussating, but form an optic chiasma, and the intestine is provided with a spiral valve. In all the species there is one dorsal and one anal fin, separate from the caudal. The teeth are small or wanting, the body naked or covered with bony plates; the caudal fin is usually heterocercal, and on the tail are rhombic plates. To this order, as thus defined, about half of the extinct Ganoids belong, as well as the modern degenerate forms known as sturgeons and perhaps the paddle-fishes, which are apparently derived from fishes with rhombic enameled scales. The species extend from the Upper Carboniferous to the present time, being most numerous in the Triassic.

At this point in Woodward's system diverges a descending series, characterized as a whole by imperfect squamation and elongate form, this leading through the synthetic type of Chondrosteidæ to the modern sturgeon and paddle-fish, which are regarded as degenerate types.

The family of Saurorhynchidæ contains pike-like forms, with long jaws, and long conical teeth set wide apart. The tail is not heterocercal, but short-diphycercal; the bones of the head are covered with enamel, and those of the roof of the skull form a continuous shield. The opercular apparatus is much reduced, and there are no branchiostegals. The fins are all small, without fulcra, and the skin has isolated longitudinal series of bony scutes, but is not covered with continuous scales. The principal genus is Saurorhynchus (= Belonorhynchus; the former being the earlier name) from the Triassic. Saurorhynchus acutus from the English Triassic is the best known species.

The family of Chondrosteidæ includes the Triassic precursors 18of the sturgeons. The general form is that of the sturgeon, but the body is scaleless except on the upper caudal lobe, and there are no plates on the median line of the skull. The opercle and subopercle are present, the jaws are toothless, and there are a few well-developed caudal rays. The caudal has large fulcra. The single well-known species of this group, Chondrosteus acipenseroides, is found in the Triassic rocks of England and reaches a length of about three feet. It much resembles a modern sturgeon, though differing in several technical respects. Chondrosteus pachyurus is based on the tail of a species of much larger size and Gyrosteus mirabilis, also of the English Triassic, is known from fragments of fishes which must have been 18 to 20 feet in length.

Fig. 5.—Chondrosteus acipenseroides Egerton. Family Chondrosteidæ. (After Woodward.)

The sturgeons constitute the recent family of Acipenseridæ, characterized by the prolonged snout and toothless jaws and the presence of four barbels below the snout. In the Acipenseridæ there are no branchiostegals and a median series of plates is present on the head. The body is armed with five rows of large bony bucklers,—each often with a hooked spine, sharpest in the young. Besides these, rhombic plates are developed on the tail, besides large fulcra. The sturgeons are the youngest of the Ganoids, not occurring before the Lower Eocene, one species, Acipenser toliapicus occurring in the London clay. About thirty living species of sturgeon are known, referred to three genera: Acipenser, found throughout the Northern Hemisphere, Scaphirhynchus, in the Mississippi Valley, and Kessleria (later called Pseudoscaphirhynchus), in Central Asia alone. Most of the species belong to the genus Acipenser, which abounds in all the rivers and seas in which salmon are found. Some of the smaller species spend their lives in the rivers, ascending 19smaller streams to spawn. Other sturgeons are marine, ascending fresh waters only for a moderate distance in the spawning season. They range in length from 2½ to 30 feet.

All are used as food, although the flesh is rather coarse and beefy. From their large size and abundance they possess great economic value. The eggs of some species are prepared as caviar.

Fig. 6.—Common Sturgeon, Acipenser sturio Mitchill. Potomac River.

The sturgeons are sluggish, clumsy, bottom-feeding fish. The mouth, underneath the long snout, is very protractile, sucker-like, and without teeth. Before it on the under side of the snout are four long feelers. Ordinarily the sturgeon feeds on mud and snails with other small creatures, but I have seen large numbers of Eulachon (Thaleichthys) in the stomach of the Columbia River sturgeon (Acipenser transmontanus). This fish and the Eulachon run in the Columbia at the same time, and the sucker-mouth of a large sturgeon will draw into it numbers of small fishes who may be unsuspiciously engaged in depositing their spawn. In the spawning season in June these clumsy fishes will often leap wholly out of the water in their play. The sturgeons have a rough skin besides five series of bony plates which change much with age and which in very old examples are sometimes lost or absorbed in the skin. The common sturgeon of the Atlantic on both shores is Acipenser sturio. Acipenser huso and numerous other species are found in Russia and Siberia. The great sturgeon of the Columbia is Acipenser transmontanus, and the great sturgeon of Japan Acipenser kikuchii. Smaller species are found farther south, as in the Mediterranean and along the Carolina coast. Other small species abound in rivers and lakes. Acipenser rubicundus is found throughout the Great Lake region and the Mississippi Valley, never entering the sea. It is four to six feet long, and at Sandusky, Ohio, in one season 14,000 sturgeons were taken 20in the pound nets. A similar species, Acipenser mikadoi, is abundant and valuable in the streams of northern Japan.

Fig. 7.—Lake Sturgeon, Acipenser rubicundus Le Sueur. Ecorse, Mich.

In the genus Acipenser the snout is sharp and conical, and the shark-like spiracle is still retained.

Fig. 8.—Shovel-nosed Sturgeon. Scaphirhynchus platyrhynchus (Rafinesque). Ohio River.

The shovel-nosed sturgeon (Scaphirhynchus platyrhynchus) has lost the spiracles, the tail is more slender, its surface wholly bony, and the snout is broad and shaped like a shovel. The single species of Scaphirhynchus abounds in the Mississippi Valley, a fish more interesting to the naturalist than to the fisherman. It is the smallest of our sturgeons, often taken in the nets in large numbers.

In Scaphirhynchus the tail is covered by a continuous coat of mail. In Kessleria^[6] fedtschenkoi, rossikowi, and other Asiatic species the tail is not mailed.

Order Selachostomi: the Paddle-fishes.—Another type of Ganoids, allied to the sturgeons, perhaps still further degenerate, is that of the paddle-fishes, called by Cope Selachostomi (σέλαχος, shark; στόμα, mouth). This group consists of a single family, Polyodontidæ, having apparently little in common with the other Ganoids, and in appearance still more suggestive of the sharks. The common name of paddle-fishes is derived from the long flat blade in which the snout terminates. This extends far beyond the mouth, is more or less sensitive, and is 21used to stir up the mud in which are found the minute organisms on which the fish feeds. Under the paddle are four very minute barbels corresponding to those of the sturgeons. The vernacular names of spoonbill, duckbill cat, and shovel-fish are also derived from the form of the snout. The skin is nearly smooth, the tail is heterocercal, the teeth are very small, and a long fleshy flap covers the gill-opening. The very long and slender gill-rakers serve to strain the food (worms, leeches, water-beetles, crustaceans, and algæ) from the muddy waters from which they are taken. The most important part of this diet consists of Entomostracans. The single American species, Polyodon spathula, abounds through the Mississippi Valley in all the larger streams. It reaches a length of three or four feet. It is often taken in the nets, but the coarse tough flesh, like that of our inferior catfish, is not much esteemed. In the great rivers of China, the Yangtse and the Hoang Ho, is a second species, Psephurus gladius, with narrower snout, fewer gill-rakers, and much coarser fulcra on the tail. The habits, so far as known, are much the same.

Fig. 9.—Paddle-fish, Polyodon spathula (Walbaum). Ohio River.

Fig. 10.—Paddle-fish. Polyodon Spathula (Walbaum). Ohio River.

Fig. 11.—Psephurus gladius Günther. Yangtse River. (After Günther.)

Crossopholis magnicaudatus of the Green River Eocene shales is a primitive member of the Polyodontidæ. Its rostral blade 22is shorter than that of Polyodon, and the body is covered with small thin scales, each in the form of a small grooved disk with several posterior denticulations, arranged in oblique series but not in contact. The scales are quadrate in form, and more widely separated anteriorly than posteriorly. As in Polyodon, the teeth are minute and there are no branchiostegals. The squamation of this fish shows that Polyodon as well as Acipenser may have sprung from a type having rhombic scales. The tail of a Cretaceous fish, Pholidurus disjectus from the Cretaceous of Europe, has been referred with doubt to this family of Polyodontidæ.

Order Pycnodonti.—In the extinct order Pycnodonti, as recognized by Dr. O. P. Hay, the notochord is persistent and without ossification, the body is very deep, the teeth are always blunt, the opercular apparatus is reduced, the dorsal fin many-rayed, and the fins without fulcra. The scales are rhombic, but are sometimes wanting, at least on the tail. Many genera and species of Pycnodontidæ are described, mostly from Triassic and Jurassic rocks of Europe. Leading European genera are Pycnodus, Typodus (Mesodon), Gyrodus, and Palæobalistum. The numerous American species belong to Typodus, Cœlodus, Pycnodus, Hadrodus, and Uranoplosus. These forms have no affinity with Balistes, although there is some resemblance in appearance, which has suggested the name of Palæobalistum.

Fig. 12.—Gyrodus hexagonus Agassiz. Family Pycnodontidæ. Lithographic Shales.

23Woodward places these fishes with the Semionotidæ and Halecomorphi in his suborder of Protospondyli. It seems preferable, however, to consider them as forming a distinct order.

Fig. 13.—Mesturus verrucosus Wagner. Family Pycnodontidæ. (After Woodward.)

Order Lepidostei.—We may place, following Eastman's edition of Zittel, the allies and predecessors of the garpike in a single order, for which Huxley's name Lepidostei may well be used. In this group the notochord is persistent, and the vertebræ are in various degrees of ossification and of different forms. The opercles are usually complete, the branchiostegals present, and there is often a gular plate. There is no infraclavicle and the jaws have sharp teeth. The fins have fulcra, and the supports of the fins agree in number with the rays. The tail is more or less heterocercal. The scales are rhombic, arranged in oblique series, which are often united above and below with peg-and-socket articulations. This group contains among recent fishes only the garpikes (Lepisosteus). They are closely allied to the Palæoniscidæ, but the skeleton is more highly ossified. On the other hand they approach very closely to the ancestors of the bowfin, Amia. One genus, Acentrophorus, appears in the Permian; the others are scattered through Mesozoic and Tertiary rocks, the isolated group of gars still persisting. In the gars the vertebræ are concavo-convex, with ball-and-socket joints. In the others the vertebræ are incomplete or else double-concave, as in fishes generally.

24For the group here called Lepidostei numerous other names have been used corresponding wholly or in part. Rhomboganoidea of Gill covers nearly the same groups; Holostei of Müller and Hyoganoidea of Gill include the Halecomorphi also; Ginglymodi of Cope includes the garpikes only, while Ætheospondyli of Woodward includes the Aspidorhynchidæ and the garpikes.

Fig. 14.—Semionotus kapffi Fraas, restored. Family Semionotidæ. (After Fraas, per Nicholson.)

The Semionotidæ (Stylodontidæ) are robust-bodied Ganoids, having the vertebræ developed as rings, the jaws with several rows of teeth, those of the outer row styliform.

Semionotus bergeri is a well-known species, with the body moderately elongate. Semionotus agassizi and many other species occur in the Triassic of the Connecticut valley and in New Jersey. The body is very deep in the related genus Dapedium, and the head is covered with strong bony plates. Dapedium politum is a well-known species of the English Triassic. Tetragonolepis (Pleurolepis) is a similar form, very deep and compressed, with strong, firm scales.

In the extinct family of Lepidotidæ the teeth are conical or chisel-shaped, while blunt or molar teeth are on the inside of the mouth, which is small, and the suspensorium of the mandible is vertical or inclined forward. The body is robust-fusiform, covered with rhomboid scales; the vertebræ form rings about the notochord; the teeth are either sharp or blunt. The dorsal fin is short, with large fulcra.

The best known of the numerous genera are Lepidotes, rather elongate in body, with large, blunt teeth. Of the many species of Lepidotes, Lepidotes elvensis abounds in the English and German Triassic, and Lepidotes minor in the English Triassic. Another well-known European species is Lepidotes mantelli.

25

Fig. 15.—Dapedium politum Leach, restored. Family Semionotidæ. (After Woodward.)

26The Isopholidæ (Eugnathidæ) differ from the families last named in the large pike-like mouth with strong teeth. The mandibular suspensorium is inclined backwards. The body is elongate, the vertebræ forming incomplete rings; the dorsal fin is short with large fulcra.

Isopholis dentosus is found with numerous other species in the British Triassic. Caturus furcatus is especially characteristic of Triassic rocks in Germany. Ptycholepis marshi occurs in the Connecticut valley.

Fig. 16.—Tetragonolepis semicinctus Brown. Lias. Family Semionotidæ. (After Woodward.)

The Macrosemiidæ are elongate fishes with long dorsal fin, the numerous species being found in the Triassic, Jurassic, and Cretaceous of Europe. Macrosemius rostratus has a very high, continuous dorsal. Macropistius arenatus is found in the Cretaceous of Texas, the only American species known. Prominent European genera are Notagogus, Ophiopsis, and Petalopteryx.

27

Fig. 17.—Isopholis orthostomus (Agassiz). Lias. (After Woodward.)

Fig. 18.—The Long-nosed Garpike, Lepisosteus osseus (Linnæus). Fox River, Wisconsin. (From nature; D. S. Jordan and M. L. McDonald, 1874.)

28Intermediate between the allies of the gars and the modern herrings is the large extinct family of Pholidophoridæ, referred by Woodward to the Isospondyli, and by Eastman to the Lepidostei. These are small fishes, fusiform in shape, chiefly of the Triassic and Jurassic. The fins are fringed with fulcra, the scales are ganoid and rhombic, and the vertebræ reduced to rings. The mouth is large, with small teeth, and formed as in the Isospondyli. The caudal is scarcely heterocercal.

Fig. 19.—Caturus elongatus Agassiz. Jurassic. Family Isopholidæ. (After Zittel.)

Fig. 20.—Notagogus pentlandi Agassiz. Jurassic. Family Macrosemiidæ. (After Woodward.)

Fig. 21.—Ptycholepis curtus Egerton. Lias. Family Isopholidæ. (After Woodward.)

Of Pholidophorus, with scales joined by peg-and-socket joints and uniform in size, there are many species. Pholidophorus latiusculus and many others are found in the Triassic of England and the Continent. Pholidophorus americanus occurs in the 29Jurassic of South Dakota. Pleuropholis, with the scales on the lateral line, which runs very low, excessively deepened, is also widely distributed. I have before me a new species from the Cretaceous rocks near Los Angeles. The Archæomænidæ differ from Pholidophoridæ in having cycloid scales. In both families the vertebræ are reduced to rings about the notochord. From fishes allied to the Pholidophoridæ the earliest Isospondyli are probably descended.

Fig. 22.—Pholidophorus crenulatus Egerton. Lias. (After Woodward.)

In the Aspidorhynchidæ the snout is more or less produced, the mandible has a distinct presymphysial bone, the vertebræ are double-concave or ring-like, and the fins are without fulcra. This family constitutes the suborder Ætheospondyli. In form these fishes resemble Albula and other modern types, but have mailed heads and an ancient type of scales. Two genera are well known, Aspidorhynchus and Belonostomus. Aspidorhynchus acutirostris reaches a length of three feet, and is found in the Triassic lithographic stone of Bavaria. Other species occur in rocks of Germany and England.

Belonostomus has the snout scarcely produced. Belonostomus sphyrænoides is the best known of the numerous species, all of the Triassic, Jurassic, and Cretaceous.

Family Lepisosteidæ.—The family of Lepisosteidæ, constituting the suborder Ginglymodi (γιγγλυμός, hinge), is characterized especially by the form of the vertebræ.

These are opisthocœlian, convex in front and concave behind, as in reptiles, being connected by ball-and-socket joints. The tail is moderately heterocercal, less so than in the Halecomorphi, and the body is covered with very hard, diamond-shaped, enameled 30scales in structure similar to that of the teeth. A number of peculiar characters are shown by these fishes, some of them having often been regarded as reptilian traits. Notable features are the elongate, crocodile-like jaws, the upper the longer, and both armed with strong teeth. The mandible is without presymphysial bone. The fins are small with large fulcra, and the scales are nearly uniform in size.

All the species belong to a single family, Lepisosteidæ, which includes the modern garpikes and their immediate relatives, some of which occur in the early Tertiary. These voracious fishes are characterized by long and slender cylindrical bodies, with enameled scales and mailed heads and heterocercal tail. The teeth are sharp and unequal. The skeleton is well ossified, and the animal itself is extremely voracious. The vertebræ, reptile-like, are opisthocœlian, that is, convex in front, concave behind, forming ball-and-socket joints. In almost all other fishes they are amphicœlian or double-concave, the interspace filled with gelatinous substance. The recent species, and perhaps all the extinct species also, belong to the single genus Lepisosteus (more correctly, but also more recently, spelled Lepidosteus). Of existing forms there are not many species, three to five at the most, and they swarm in the lakes, bayous, and sluggish streams from Lake Champlain to Cuba and along the coast to Central America. The best known of the species is the long-nosed garpike, Lepisosteus osseus, which is found throughout most of the Great Lake region and the Mississippi Valley, and in which the long and slender jaws are much longer than the rest of the head. The garpike frequents quiet waters and is apparently of sleepy habit. It often lies quiet for a long time, carried around and around by the eddies. It does not readily take the hook and seldom feeds in the aquarium. It feeds on crayfishes and small fishes, to which it is exceedingly destructive, as its bad reputation indicates. Fishermen everywhere destroy it without mercy. Its flesh is rank and tough and unfit even for dogs.

In the young garpike the caudal fin appears as a second dorsal and anal, the filamentous tip of the tail passing through and beyond it.

The short-nosed garpike, Lepisosteus platystomus, is generally 31common throughout the Mississippi Valley. It has a short broad snout like the alligator-gar, but seldom exceeds three feet in length. In size, color, and habits it agrees closely with the common gar, differing only in the form of the snout. The form is subject to much variation, and it is possible that two or more species have been confounded.

Fig. 23.—Alligator-gar, Lepisosteus tristœchus (Bloch). Cuba.

The great alligator-gar, Lepisosteus tristœchus, reaches a length of twenty feet or more, and is a notable inhabitant of the streams about the Gulf of Mexico. Its snout is broad and relatively wide, and its teeth are very strong. It is very destructive to all sorts of food-fishes. Its flesh is worthless, and its enameled scales resist a spear or sometimes even shot. It breathes air to a certain extent by its lungs, but soon dies in foul water, not having the tenacity of life seen in Amia.

Embryology of the Garpike.—Mr. Alexander Agassiz has given an account of the embryology of the garpike, of which the following is an abstract:

"The garpike comes up the St. Lawrence in May, lays its eggs about the 20th, and then disappears. The eggs are large, viscous, stick fast in an isolated way to whatever they fall upon, and look much like those of toads, having a large outer membrane and a small yolk. Artificial fecundation failed, but about 500 naturally-laid eggs were secured, of which all but 30 perished through mold. The young began to hatch in six days. Out of 30 young hatched, 27 lived until the 15th of July. Connection with the sharks appears in the similarity of the branchial arches and by the presence of the lateral fold in which the pectoral fins are formed; the way the tail is developed is very like that of the bony fishes. Among the Ganoids it appears, as well as in ordinary fishes, the dorsal cord is straight at first, then assumes a slightly upward 32curve at the extremity, when finally there appears the beginning of a lobe underneath, pointing to a complete heterocercal tail. All this is as in the bony fishes, but this is the permanent condition of the garpike, while in the bony fishes the extremity of the dorsal cord becomes extinct. The mode of development of the pectoral lobe (very large in this species) furnishes another resemblance. In the brain, and in the mode of formation of the gills, a likeness to the sharks is noticeable. The young garpikes move very slowly, and seem to float quietly, save an exceedingly rapid vibration of the pectorals and the tip of the tail. They do not swim about much, but attach themselves to fixed objects by an extraordinary horseshoe-shaped ring of sucker-appendages about the mouth. These appendages remain even after the snout has become so extended that the ultimate shape is hinted at; and furthermore, it is a remnant of this feature that forms the fleshy bulb at the end of the snout in the adult. The investigations thus far show that the young garpike has many characteristics in common with the sharks and skates, but it is not so different from the bony fishes as has been supposed."

Fossil Garpikes.—A number of fossil garpikes, referred by Cope to the genus Clastes and by Eastman and Woodward to Lepidosteus, are found in the Eocene of Europe and America. The most perfect of these remains is called Lepisosteus atrox, upward of four feet long, as large as an alligator-gar, which the species much resembles. Although found in the Eocene, Dr. C. R. Eastman declares that "it has no positively archaic features. If we inquire into the more remote or pre-Eocene history of Lepidosteids, palæontology gives no answer. They blossom forth suddenly and fully differentiated at the dawn of the Tertiary, without the least clue to their ancestry, unheralded and unaccompanied by any intermediate forms, and they have remained essentially unchanged ever since."

Another fossil species is Lepisosteus fimbriatus, from the Upper Eocene of England. Scales and other fragments of garpikes are found in Germany, Belgium, and France, in Eocene and Miocene rocks. On some of these the nominal genera Naisia, Trichiurides, and Pneumatosteus are founded. Clastes, regarded by Eastman as fully identical with Lepisosteus, is said 33to have the "mandibular ramus without or with a reduced fissure of the dental foramen, and without the groove continuous with it in Lepisosteus. One series of large teeth, with small ones external to them on the dentary bone." Most of the fossil forms belong to Clastes, but the genus shows no difference of importance which will distinguish it from the ordinary garpike.

Fig. 24.—Lower jaw of Amia calva Linnæus, showing the gular plate.

Order Halecomorphi.—To this order belong the allies, living or extinct, of the bowfin (Amia), having for the most part cycloid scales and vertebræ approaching those of ordinary fishes. The resemblance to the Isospondyli, or herring group, is indicated in the name (Halec, a herring; μορφή, form). The notochord is persistent, the vertebræ variously ossified. The opercles are always complete. The branchiostegals are broad and there is always a gular plate. The teeth are pointed, usually strong. There is no infraclavicle. Fulcra are present or absent. The supports of the dorsal and anal are equal in number to the rays. Tail heterocercal. Scales thin, mostly cycloid, but bony at base, not jointed with each other. Mandible complex, with well-developed splenial rising into a coronoid process, which is completed by a distinct coronoid bone. Pectoral fin with more than five actinosts; scales ganoid or cycloid. In the living forms the air-bladder is connected with the œsophagus through life; optic chiasma present; intestine with a spiral valve. This group corresponds to the Amioidei of Lütken 34and essentially to the Cycloganoidei of Gill. The Protospondyli (προτός, before; σπόνδυλος, vertebra) of Woodward contains essentially the same elements.

Pachycormidæ.—In the family of Pachycormidæ the notochord is persistent, the ethmoids and vomer fused and projecting between the maxillaries to form the prominent snout, the teeth large, the body fusiform, the dorsal short, with slender rays and few fulcra or none, and the scales are thin and rhombic. The numerous species are characteristic of the Triassic, Jurassic, and Cretaceous. In Sauropsis (longimana) the body is elongate, and the pectoral fins are large and sickle-shaped. Euthynotus has small fulcra. In Pachycormus (macropterus, esocinus, etc.) the form is robust and the ventral fins are wanting. In Hypsycormus ventrals are present, and the caudal deeply forked.

In the American family of Protosphyrænidæ the jaws are armed with very strong teeth, as in the Barracuda, which, however, the species do not resemble in other respects. Protosphyræna nitida, perniciosa, and numerous other extinct forms, some of them of large size, were voracious inhabitants of the Cretaceous seas, and are found fossil, especially in North Carolina and Kansas. Numerous species called Erisichthe and Pelecopterus are all referred by Hay to Protosphyræna. In this family the scapula and coracoids are ossified, and perhaps the vertebræ also, and, as Dr. Hay has recently suggested, the Protosphyrænidæ may really belong to the Isospondyli. In any event, they stand on the border-line between the most fish-like of the Ganoids and the most archaic of the bony fishes.

The Liodesmidæ (genus Liodesmus) are much like Amia, but the notochord is persistent, its sheath without ossification. Liodesmus gracilis and L. sprattiformis occur in the lithographic stones of Bavaria. Woodward places Liodesmus with Megalurus among the Amiidæ.

The Bowfins: Amiidæ.—The Amiidæ have the vertebræ more complete. The dorsal fin is many-rayed and is without distinct fulcra. The diamond-shaped enameled scales disappear, giving place to cycloid scales, which gradually become thin and membranous in structure. A median gular plate is developed between the branchiostegals. The tail is moderately heterocercal, and the head covered with a bony coat of mail.

35The family of Amiidæ contains a single recent species, Amia calva, the only living member of the order Halecomorphi. The bowfin, or grindle, is a remarkable fish abounding in the lakes and swamps of the Mississippi Valley, the Great Lake region, and southward to Virginia, where it is known by the imposing but unexplained title of John A. Grindle. In the Great Lakes it is usually called "dogfish," because even the dogs will not eat it, and "lawyer," because, according to Dr. Kirtland, "it will bite at anything and is good for nothing when caught."

The bowfin reaches a length of two and one half feet, the male being smaller than the female and marked by an ocellated black spot on the tail. Both sexes are dark mottled green in color. The flesh of the species is very watery, pasty, much of the substance evaporating when exposed to the air. It is ill-flavored, and is not often used as food. The species is very voracious and extremely tenacious of life. Its well-developed lung enables it to breathe even when out of the water, and it will live in the air longer than any other fish of American waters, longer even than the horned pout (Ameiurus) or the mud-minnow (Umbra). As a game fish the grindle is one of the very best, if the angler does not care for the flesh of what he catches, it being one of the hardest fighters that ever took the hook.

Fig. 25.—Bowfin (female), Amia calva Linnæus. Lake Michigan.

The Amiidæ retain many of the Ganoid characters, though approaching more nearly than any other of the Ganoids to the modern herring tribe. For this reason the name Halecomorphi (shad-formed) was given to this order by Professor Cope. The gular plate found in Amia and other Ganoids reappears in the herring-like family of Elopidæ, which includes the tarpon and the ten-pounder.

36Woodward unites the extinct genera called Cyclurus, Notæus, Amiopsis, Protamia, Hypamia, and Pappichthys with Amia. Pappichthys (corsoni, etc.), from the Wyoming Eocene, is doubtless a valid genus, having but one row of teeth in each jaw, and Amiopsis is also recognized by Hay. Woodward refers to Amia the following extinct species: Amia valenciennesi, from the Miocene of France; Amia macrocephala, from the Miocene of Bohemia; and Amia ignota, from the Eocene of Paris. Other species of Amia are known from fragments. Several of these are from the Eocene of Wyoming and Colorado. Some of them have a much shorter dorsal fin than that of Amia calva and may be generically different.

Fig. 26.—Megalurus elegantissimus Wagner. Family Amiidæ. (After Zittel.)

The genus Megalurus differs from Amia in the still shorter dorsal fin, less than one-third the length of the back. The body is elongate and much depressed. Megalurus lepidotus and several other species are found in the lithographic stones of Bavaria and elsewhere.

The Oligopleuridæ.—In the extinct family Oligopleuridæ the scales are cycloid, the bones of the head scarcely enameled, and the vertebræ well ossified. Fulcra are present, and the mouth is large, with small teeth. The genera are Oligopleurus, Ionoscopus, and Spathiurus, the species not very numerous and chiefly of the Cretaceous. Ionoscopus cyprinoides of the lithographic shales of Bavaria is a characteristic species.

From the three families last named, with the Pholidophoridæ, there is an almost perfect transition from the Ganoid fishes to teleosteans of the order of Isospondyli, the primitive order from which all other bony fishes are perhaps descended. The family of Leptolepidæ, differing from Oligopleuridæ in the absence of fulcra, is here placed with the Isospondyli, but it might about as well be regarded as Ganoid.

The Subclass Teleostei, or Bony Fishes.—The fishes which still remain for discussion constitute the great subclass or series of Teleostei (τελεός, true; οστέον, bone), or bony fishes. They lack wholly or partly the Ganoid traits, or show them only in the embryo. The tail is slightly, if at all, heterocercal; the actinosts of the pectoral fins are few and large, rarely over five in number, except among the eels; the fulcra disappear; the air-bladder is no longer cellular, except in very rare cases, nor does it assist in respiration. The optic nerves are separate, one running to each eye without crossing; the skeleton is almost entirely bony, the notochord usually disappearing entirely with age; the valves in the arterial bulb are reduced in number, and the spiral valve of the intestines disappears. Traces of each of the Ganoid traits may persist somewhere in some group, but as a whole we see a distinct specialization and a distinct movement toward the fish type, with the loss of characters distinctive of sharks, Dipnoans, and Ganoids. In a general way the skeleton of all Teleosts corresponds with that of the striped bass (see Figs. 22, 23, Vol. I), and the visceral anatomy is in all cases sufficiently like that of the sunfish (Fig. 16, Vol. I).

The mesocoracoid or precoracoid arch, found in all Ganoids, persists in the less specialized types of bony fishes, although no trace of it is found in the perch-like forms. With all this, there is developed among the bony fishes an infinite variety in details of structure. For this reason the Teleostei must be broken into many orders, and these orders are very different in value and in degrees of distinctness, the various groups being joined by numerous and puzzling intergradations.

38Order Isospondyli.—Of the various subordinate groups of bony fishes, there can be no question as to which is most primitive in structure, or as to which stands nearest the orders of Ganoids. Earliest of the bony fishes in geological time is the order of Isospondyli (ἴσος, equal; σπόνδυλος, vertebra), containing the allies, recent or fossil, of the herring and the trout. This order contains those soft-rayed fishes in which the ventral fins are abdominal, a mesocoracoid or precoracoid arch is developed, and the anterior vertebræ are unmodified and essentially similar to the others. The orbitosphenoid is present in all typical forms. In certain forms of doubtful affinity (Iniomi) the mesocoracoid is wanting or lost in degeneration. Through the Isospondyli all the families of fishes yet to be considered are apparently descended, their ancestors being Ganoid fishes and, still farther back, the Crossopterygians.

Woodward gives this definition of the Isospondyli: "Notochord varying in persistence, the vertebral centra usually complete, but none coalesced; tail homocercal, but hæmal supports not much expanded or fused. Symplectic bone present, mandible simple, each dentary consisting only of two elements (dentary and articulo-angular), with rare rudiments of a splenoid on the inner side. Pectoral arch suspended from the cranium; precoracoid (mesocoracoid) arch present; infraclavicular plates wanting. Pelvic (ventral) fins abdominal. Scales ganoid only in the less specialized families. In the living forms air-bladder connected with the œsophagus in the adult; optic nerves decussating (without chiasma), and intestine either wanting spiral valve or with an incomplete representative of it."

The Classification of the Bony Fishes.—The classification of fishes has been greatly complicated by the variety of names applied to groups which are substantially but not quite identical one with another. The difference in these schemes of classification lies in the point of view. In all cases a single character must be brought to the front; such characters never stand quite alone, and to lay emphasis on another character is to make an alteration large or small in the name or in the boundaries of a class or order. Thus the Ostariophysi with the Isospondyli, Haplomi, and a few minor groups make up the great division of the Abdominales. These are fishes in which the 39ventral fins are abdominal, that is, inserted backward, so that the pelvis is free from the clavicle, the two sets of limbs being attached to different parts of the skeleton. Most of the abdominal fishes are also soft-rayed fishes, that is, without consecutive spines in the dorsal and anal fins, and they show a number of other archaic peculiarities. The Malacopterygians (μαλακός, soft; πτερύξ, fin) of Cuvier therefore correspond very nearly to the Abdominales. But they are not quite the same, as the spiny-rayed barracudas and mullets have abdominal ventrals, and many unquestioned thoracic or jugular fishes, as the sea-snails and brotulids, have lost, through degeneration, all of their fin-spines.

In nearly but not quite all of the Abdominal fishes the slender tube connecting the air-bladder with the œsophagus persists through life. This character defines Müller's order of Physostomi (φυσός, bladder; στόμα, mouth), as opposed to his Physoclysti (φυσός, bladder; κλεῖστός, closed), in which this tube is present in the embryo or larva only. Thus the Thoracices and Jugulares, or fishes having the ventrals thoracic or jugular, together correspond almost exactly to the Acanthopterygians, (ακανθα, spine; πτερύξ, fin), or spiny-rayed fishes of Cuvier, or to the Physoclysti of Müller. The Malacopterygians, the Abdominales, and the Physostomi are in the same way practically identical groups. As the spiny-rayed fishes have mostly ctenoid scales, and the soft-rayed fishes cycloid scales, the Physostomi correspond roughly to Agassiz's Cycloidei, and the Physoclysti to his Ctenoidei.

But in none of these cases is the correspondence perfectly exact, and in any system of classification we must choose characters for primary divisions so ancient and therefore so permanent as to leave no room for exceptions. The extraordinary difficulty of doing this, with the presence of most puzzling intergradations, has led Dr. Gill to suggest that the great body of bony fishes, soft-rayed and spiny-rayed, abdominal, thoracic, and jugular alike, be placed in a single great order which he calls Teleocephali (τελεός, perfect; κεφαλή, head). The aberrant forms with defective skull and membrane-bones he would separate as minor offshoots from this great mass with the name of separate orders. But while the divisions of Teleocephali 40are not strongly differentiated, their distinctive characters are real, ancient, and important, while those of the aberrant groups, called orders by Gill (as Plectognathi, Pediculati, Hemibranchii), are relatively modern and superficial, which is one reason why they are more easily defined. There seems to us no special advantage in the retention of a central order Teleocephali, from which the divergent branches are separated as distinct orders.

While our knowledge of the osteology and embryology of most of the families of fishes is very incomplete, it is evident that the relationships of the groups cannot be shown in any linear series or by any conceivable arrangement of orders and suborders. The living teleost fishes have sprung from many lines of descent, their relationships are extremely diverse, and their differences are of every possible degree of value. The ordinary schemes have magnified the value of a few common characters, at the same time neglecting other differences of equal value. No system of arrangement which throws these fishes into large groups can ever be definite or permanent.

Relationships of Isospondyli.—For our purposes we may divide the physostomous fishes as understood by Müller into several orders, the most primitive, the most generalized, and economically the most important being the order of Isospondyli. This order contains those bony fishes which have the anterior vertebræ unaltered (as distinguished from the Ostariophysi), the skull relatively complete, or at least not eel-like, the mesocoracoid typically developed, but atrophied in deep-sea forms and finally lost, the orbitosphenoid present. In all the species the ventral fins are abdominal and normally composed of more than six rays; the air-duct is developed. The scales are chiefly cycloid and the fins are without true spines. In many ways the order is more primitive than Nematognathi, Plectospondyli, or Apodes. It is certain that it began earlier in geological time than any of these. On the other hand, the Isospondyli are closely connected through the Berycoidei with the highly specialized fishes. The continuity of the natural series is therefore interrupted by the interposition of the side branches of Ostariophysans and eels before considering the Haplomi and the other transitional forms. The forms called Iniomi, which lack the mesocoracoid and the 41orbitosphenoid, have been lately transferred to the Haplomi by Boulenger. This arrangement is probably a step in advance.

Ganoid traits are present in certain families of Isospondyli. Among these are the gular plate (found in Amia and the Elopidæ), doubtless derived from the similar structure in earlier Ganoids; additional valves in the arterial bulb in the cellular air-bladder of Notopterus and Osteoglossum, the spiral intestinal valve in Chirocentridæ, and the ganoid scales of the extinct Leptolepidæ.

The Clupeoidea.—The Isospondyli are divisible into numerous families, which may be grouped roughly under three subdivisions, Clupeoidea, the herring-like forms; the Salmonoidea, the trout-like forms; and the Iniomi, or lantern-fishes, and their allies. The last-named group should probably be removed from the order of Isospondyli. In the Clupeoidea, the allies of the great family of the herring, the shoulder-girdle is normally developed, retaining the mesocoracoid arch on its inner edge, and through the post-temporal is articulated above with the cranium. The fishes in this group lack the adipose fin which is characteristic of most of the higher or salmon-like families.

Fig. 27.—Leptolepis dubius Blainville, Lithographic Stone. (After Woodward.)

The Leptolepidæ.—Most primitive of the Isospondyli is the extinct family of Leptolepidæ, closely allied to the Ganoid families of Pholidophoridæ and Oligopleuridæ. It is composed of graceful, herring-like fishes, with the bones of the head thin but covered with enamel, and the scales thin but firm and enameled on their free portion. There are no fulcra and there is no lateral line. The vertebræ are well developed, but always pierced by the notochord. The genera are Lycoptera, Leptolepis, Æthalion, and Thrissops. In Lycoptera of the Jurassic of China the 42vertebral centra are feebly developed, and the dorsal fin short and posterior. In Leptolepis the anal is short and placed behind the dorsal. There are many species, mostly from the Triassic and lithographic shales of Europe, one being found in the Cretaceous. Leptolepis coryphænoides and Leptolepis dubius are among the more common species. Æthalion (knorri) differs in the form of the jaws. In Thrissops the anal fin is long and opposite the dorsal. Thrissops salmonea is found in the lithographic stone; Thrissops exigua in the Cretaceous. In all these early forms there is a hard casque over the brain-cavity, as in the living types, Amia and Osteoglossum.

Fig. 28.—Ten-pounder, Elops saurus L. An ally of the earliest bony fishes. Virginia.

Fig. 29.—A primitive Herring-like fish, Holcolepis lewesiensis, Mantell, restored. Family Elopidæ. English Chalk. (After Woodward.)

The Elopidæ.—The family of Elopidæ contains large fishes herring-like in form and structure, but having a flat membrane-bone or gular plate between the branches of the lower jaw, as in the Ganoid genus Amia. The living species are few, abounding in the tropical seas, important for their size and numbers, though not valued as food-fishes save to those who, like the Hawaiians and Japanese, eat fishes raw. These people prefer 43for that purpose the white-meated or soft-fleshed forms like Elops or Scarus to those which yield a better flavor when cooked.

The ten-pounder (Elops saurus), pike-like in form but with very weak teeth, is found in tropical America. Elops machnata, the jack mariddle, the awaawa of the Hawaiians, abounding in the Pacific, is scarcely if at all different.

Fig. 30.—Tarpon or Grande Écaille, Tarpon atlanticus Cuv. & Val. Florida.

The tarpon, called also grande écaille, silver-king, and sable (Tarpon atlanticus), is a favorite game-fish along the coasts of Florida and Carolina. It takes the hook with great spirit, and as it reaches a length of six feet or more it affords much excitement to the successful angler. The very large scales are much used in ornamental work.

A similar species of smaller size, also with the last ray of the dorsal very much produced, is Megalops cyprinoides of the East Indies. Other species occur in the South Seas.

Numerous fossil genera related to Elops are found in the Cretaceous and Tertiary rocks. Holcolepis lewesiensis (wrongly called Osmeroides) is the best-known European species. Numerous species are referred to Elopopsis. Megalops prisca and species of Elops also occur in the London Eocene.

In all these the large parietals meet along the median line of the skull. In the closely related family of Spaniodontidæ the parietals are small and do not meet. All the species of this group, united by Woodward with the Elopidæ, are extinct. These fishes preceded the Elopidæ in the Cretaceous period. Leading genera are Thrissopater and Spaniodon, the latter armed with large teeth. Spaniodon blondeli is from the Cretaceous 44of Mount Lebanon. Many other species are found in the European and American Cretaceous rocks, but are known from imperfect specimens only.

Sardinius, an American Cretaceous fossil herring, may stand near Spaniodon. Rhacolepis buccalis and Notelops brama are found in Brazil, beautifully preserved in concretions of calcareous mud supposed to be of Cretaceous age.

The extinct family of Pachyrhizodontidæ is perhaps allied to the Elopidæ. Numerous species of Pachyrhizodus are found in the Cretaceous of southern England and of Kansas.

The Albulidæ.—The Albulidæ, or lady-fishes, characterized by the blunt and rounded teeth, are found in most warm seas. Albula vulpes is a brilliantly silvery fish, little valued as food. The metamorphosis (see Fig. 112, Vol. I) which the larva undergoes is very remarkable. It is probably, however, more or less typical of the changes which take place with soft-rayed fishes generally, though more strongly marked in Albula and in certain eels than in most related forms. Fossils allied to Albula, Albula oweni, Chanoides macropomus, are found in the Eocene of Europe; Syntegmodus altus in the Cretaceous of Kansas. In Chanoides, the most primitive genus, the teeth are much fewer than in Albula. Plethodus and Thryptodus, with peculiar dental plates on the roof and floor of the mouth, probably constitute a distinct family, Thryptodontidæ. The species are found in European and American rocks, but are known from imperfect specimens only.

Fig. 31.—The Lady-fish, Albula vulpes (Linnæus). Florida.

The Chanidæ.—The Chanidæ, or milkfishes, constitute another small archaic type, found in the tropical Pacific. They are 45large, brilliantly silvery, toothless fishes, looking like enormous dace, swift in the water, and very abundant in the Gulf of California, Polynesia, and India. The single living species is the Awa, or milkfish, Chanos chanos, largely used as food in Hawaii. Species of Prochanos and Chanos occur in the Cretaceous, Eocene, and Miocene. Allied to Chanos is the Cretaceous genus Ancylostylos (gibbus), probably the type of a distinct family, toothless and with many-rayed dorsal.

Fig. 32.—Milkfish, Chanos chanos (L.). Mazatlan.

Fig. 33.—Mooneye, Hiodon tergisus Le Sueur. Ecorse, Mich.

The Hiodontidæ.—The Hiodontidæ, or mooneyes, inhabit the rivers of the central portion of the United States and Canada. They are shad-like fishes with brilliantly silvery scales and very strong sharp teeth, those on the tongue especially long. They are very handsome fishes and take the hook with spirit, but the flesh is rather tasteless and full of small bones, much like that 46of the milkfish. The commonest species is Hiodon tergisus. No fossil Hiodontidæ are known.

Fig. 34.—Istieus grandis Agassiz. Family Pterothrissidæ. (After Zittel.)

Fig. 35.—Chirothrix libanicus Pictet & Humbert. Cretaceous of Mt. Lebanon. (After Woodward.)

The Pterothrissidæ.—The Pterothrissidæ are sea-fishes like Albula, but more slender and with a long dorsal fin. They live in deep or cold waters along the coasts of Japan, where they are known as gisu. The single species is Pterothrissus gissu. The fossil genus Istieus, from the Upper Cretaceous, probably belongs near the Pterothrissidæ. Istieus grandis is the best-known species. Another ancient family, now represented by a single species, is that of the Chirocentridæ, of which the living type is Chirocentrus dorab, a long, slender, much compressed herring-like fish, with a saw-edge on the belly, found in the East Indies, in which region Chirocentrus polyodon occurs as a fossil. Numerous fossil genera related to Chirocentrus are enumerated by Woodward, most of them to be referred to the related family of Ichthyodectidæ (Saurodontidæ). Of these, Portheus, Ichthyodectes, Saurocephalus (Saurodon), and Gillicus are represented by numerous species, some of them fishes of immense size and great voracity. Portheus molossus, found in the Cretaceous of Nebraska, is remarkable for its very strong teeth. Species of other genera are represented by numerous species in the Cretaceous of both the Rocky Mountain region and of Europe.

47

Fig. 36.—Gigantic skeleton of Portheus molossus Cope. (Photograph by Charles H. Sternberg.)

48The Ctenothrissidæ.—A related family, Ctenothrissidæ, is represented solely by extinct Cretaceous species. In this group the body is robust with large scales, ctenoid in Ctenothrissa, cycloid in Aulolepis. The fins are large, the belly not serrated, and the teeth feeble. Ctenothrissa vexillifera is from Mount Lebanon. Other species occur in the European chalk. In the small family of Phractolæmidæ the interopercle, according to Boulenger, is enormously developed.

Fig. 37.—Ctenothrissa vexillifera Pictet, restored. Mt. Lebanon Cretaceous. (After Woodward.)

The Notopteridæ.—The Notopteridæ is another small family in the rivers of Africa and the East Indies. The body ends in a long and tapering fin, and, as usual in fishes which swim by 49body undulations, the ventral fins are lost. The belly is doubly serrate. The air-bladder is highly complex in structure, being divided into several compartments and terminating in two horns anteriorly and posteriorly, the anterior horns being in direct communication with the auditory organ. A fossil Notopterus, N. primævus, is found in the same region.

The Clupeidæ.—The great herring family, or Clupeidæ, comprises fishes with oblong or herring-shaped body, cycloid scales, and feeble dentition. From related families it is separated by the absence of lateral line and the division of the maxillary into three pieces. In most of the genera the belly ends in a serrated edge, though in the true herring this is not very evident, and in some the belly has a blunt edge. Some of the species live in rivers, some ascend from the sea for the purpose of spawning. The majority are confined to the ocean. Among all the genera, the one most abundant in individuals is that of Clupea, the herring. Throughout the North Atlantic are immense schools of Clupea harengus. In the North Pacific on both shores another herring, Clupea pallasi, is equally abundant, and with the same market it would be equally valuable. As salted, dried, or smoked fish the herring is found throughout the civilized world, and its spawning and feeding-grounds have determined the location of cities.

Fig. 38.—Herring, Clupea harengus L. New York.

The genus Clupea, of northern distribution, has the vertebræ in increased number (56), and there are weak teeth on the vomer. Several other genera are very closely related, but ranging farther south they have, with other characters, fewer (46 to 50) vertebræ. The alewife, or branch-herring (Pomolobus pseudoharengus), ascends the rivers to spawn and has become landlocked in 50the lakes of New York. The skipjack of the Gulf of Mexico, Pomolobus chrysochloris, becomes very fat in the sea. The species becomes landlocked in the Ohio River, where it thrives as to numbers, but remains lean and almost useless as food. The glut-herring, Pomolobus æstivalis, and the sprat, Pomolobus sprattus, of Europe are related forms.

Fig. 39.—Alewife, Pomolobus pseudoharengus (Wilson). Potomac River.

Very near also to the herring is the shad (Alosa sapidissima) of the eastern coasts of America, and its inferior relatives, the shad of the Gulf of Mexico (Alosa alabamæ), the Ohio River shad (Alosa ohiensis), very lately discovered, the Allice shad (Alosa alosa) of Europe, and the Thwaite shad (Alosa finta). In the genus Alosa the cheek region is very deep, giving the head a form different from that seen in the herring.

The American shad is the best food-fish in the family, peculiarly delicate in flavor when broiled, but, to a greater degree than occurs in any other good food-fish, its flesh is crowded with small bones. The shad has been successfully introduced into the waters of California, where it abounds from Puget Sound to Point Concepcion, ascending the rivers to spawn in May as in its native region, the Atlantic coast.

The genus Sardinella includes species of rich flesh and feeble skeleton, excellent when broiled, when they may be eaten bones and all. This condition favors their preservation in oil as "sardines." All the species are alike excellent for this purpose. The sardine of Europe is the Sardinella pilchardus, known in England as the pilchard. The "Sardina de España" of 51Cuba is Sardinella pseudohispanica, the sardine of California, Sardinella cærulea. Sardinella sagax abounds in Chile, and Sardinella melanosticta is the valued sardine of Japan.

In the tropical Pacific occur other valued species, largely belonging to the genus Kowala. The genus Harengula contains small species with very large, firm scales which do not fall when touched, as is generally the case with the sardines. Most common of these is Harengula sardina of the West Indies. Similar species occur in southern Europe and in Japan.

Fig. 40.—Menhaden, Brevoortia tyrannus (Latrobe). Wood's Hole, Mass.

In Opisthonema, the thread-herring, the last dorsal ray is much produced, as in the gizzard-shad and the tarpon. The two species known are abundant, but of little commercial importance. Of greater value are the menhaden, or the moss-bunker, Brevoortia tyrannus, inhabiting the sandy coasts from New England southward. It is a coarse and bony fish, rarely eaten when adult, although the young in oil makes acceptable sardines. It is used chiefly for oil, the annual yield exceeding in value that of whale-oil. The refuse is used as manure, a purpose for which the fishes are often taken without preparation, being carried directly to the cornfields. From its abundance this species of inferior flesh exceeds in commercial value almost all other American fishes excepting the cod, the herring, and the quinnat salmon.

One of the most complete of fish biographies is that of Dr. G. Brown Goode on the "Natural and Economic History of Menhaden."

Numerous other herring-like forms, usually with compressed bodies, dry and bony flesh, and serrated bellies, abound in the 52tropics and are largely salted and dried by the Chinese. Among these are Ilisha elongata of the Chinese coast. Related forms occur in Mexico and Brazil.

The round herrings, small herrings which have no serrations on the belly, are referred by Dr. Gill to the family of Dussumieriidæ. These are mostly small tropical fishes used as food or bait. One of these, the Kobini-Iwashi of Japan (Stolephorus japonicus), with a very bright silver band on the side, has considerable commercial importance. Very small herrings of this type in the West Indies constitute the genus Jenkinsia, named for Dr. Oliver P. Jenkins, the first to study seriously the fishes of Hawaii. Other species constitute the widely distributed genera Etrumeus and Dussumieria. Etrumeus sardina is the round herring of the Virginia coast. Etrumeus micropus is the Etrumei-Iwashi of Japan and Hawaii.

Fig. 41.—A fossil Herring, Diplomystus humilis Leidy. (From a specimen obtained at Green River, Wyo.) The scutes along the back lost in the specimen. Family Clupeidæ.

Fossil herring are plentiful and exist in considerable variety, even among the Clupeidæ as at present restricted. Histiothrissa of the Cretaceous seems to be allied to Dussumieria and Stolephorus. Another genus, from the Cretaceous of Palestine, Pseudoberyx (syriacus, etc.), having pectinated scales, should perhaps constitute a distinct subfamily, but the general structure is like that of the herring. More evidently herring-like is Scombroclupea (macrophthalma). The genus Diplomystus, with enlarged scales along the back, is abundantly represented in the Eocene shales of Green River, Wyoming. Species of similar appearance, usually but wrongly referred to the same genus, occur on the coasts of Peru, Chile, and New South Wales. A specimen of Diplomystus humilis from Green River is here 53figured. Numerous herring, referred to Clupea, but belonging rather to Pomolobus, or other non-Arctic genera, have been described from the Eocene and later rocks.

Several American fossil herring-like fishes, of the genus Leptosomus, as Leptosomus percrassus, are found in the Cretaceous of South Dakota.

Fossil species doubtfully referred to Dorosoma, but perhaps allied rather to the thread-herring (Opisthonema), being herrings with a prolonged dorsal ray, are recorded from the early Tertiary of Europe. Among these is Opisthonema doljeanum from Austria.

Fig. 42.—Hickory-shad, Dorosoma cepedianum (Le Sueur). Potomac River.

The Dorosomatidæ.—The gizzard-shad, Dorosomatidæ, are closely related to the Clupeidæ, differing in the small contracted toothless mouth and reduced maxillary. The species are deep-bodied, shad-like fishes of the rivers and estuaries of eastern America and eastern Asia. They feed on mud, and the stomach is thickened and muscular like that of a fowl. As the stomach has the size and form of a hickory-nut, the common American species is often called hickory-shad. The gizzard-shad are all very poor food-fish, bony and little valued, the flesh full of small bones. The belly is always serrated. In three of the four genera of Dorosomatidæ the last dorsal ray is much produced and whip-like. The long and slender gill-rakers serve as strainers for the mud in which these fishes find their vegetable and animal food. Dorosoma cepedianum, the common hickory-shad or 54gizzard-shad, is found in brackish river-mouths and ponds from Long Island to Texas, and throughout the Mississippi Valley in all the large rivers. Through the canals it has entered Lake Michigan. The Konoshiro, Clupanodon thrissa, is equally common in China and Japan.

The Engraulididæ.—The anchovies (Engraulididæ) are dwarf herrings with the snout projecting beyond the very wide mouth. They are small in size and weak in muscle, found in all warm seas, and making a large part of the food of the larger fish. The genus Engraulis includes the anchovy of Europe, Engraulis encrasicholus, with similar species in California, Chile, Japan, and Australia. In this genus the vertebræ are numerous, the bones feeble, and the flesh tender and oily. The species of Engraulis are preserved in oil, often with spices, or are made into fish-paste, which is valued as a relish. The genus Anchovia replaces Engraulis in the tropics. The vertebræ are fewer, the bones firm and stiff, and the flesh generally dry. Except as food for larger fish, these have little value, although existing in immense schools. Most of the species have a bright silvery band along the side. The most familiar of the very numerous species is the silver anchovy, Anchovia browni, which abounds in sandy bays from Cape Cod to Brazil. Several other genera occur farther southward, as well as in Asia, but Engraulis only is found in Europe. Fossil anchovies called Engraulis are recorded from the Tertiary of Europe.

Fig. 43.—A Silver Anchovy, Anchovia perthecata (Goode & Bean). Tampa.

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Fig. 44.—Notogoneus osculus Cope. Green River Eocene. Family Gonorhynchidæ.

56Gonorhynchidæ.—To the Isospondyli belongs the small primitive family of Gonorhynchidæ, elongate fishes with small mouth, feeble teeth, no air-bladder, small scales of peculiar structure covering the head, weak dentition, the dorsal fin small, and posterior without spines. The mesocoracoid is present as in ordinary Isospondyli. Gonorhynchus abbreviatus occurs in Japan, and Gonorhynchus gonorhynchus is found in Australia and about the Cape of Good Hope. Numerous fossil species occur. Charitosomus lineolatus and other species are found in the Cretaceous of Mount Lebanon and elsewhere. Species without teeth from the Oligocene of Europe and America are referred to the genus Notogoneus. Notogoneus osculus occurs in the Eocene fresh-water deposits at Green River, Wyoming. It bears a very strong resemblance in form to an ordinary sucker (Catostomus), for which reason it was once described by the name of Protocatostomus. The living Gonorhynchidæ are all strictly marine.

In the small family of Cromeriidæ the head and body are naked.

The Osteoglossidæ.—Still less closely related to the herring is the family of Osteoglossidæ, huge pike-like fishes of the tropical rivers, armed with hard bony scales formed of pieces like mosaic. The largest of all fresh-water fishes is Arapaima gigas of the Amazon region, which reaches a length of fifteen feet and a weight of 400 pounds. It has naturally considerable commercial importance, as have species of Osteoglossum, coarse river-fishes which occur in Brazil, Egypt, and the East Indies. Heterotis nilotica is a large fish of the Nile. In some or all of these the air-bladder is cellular or lung-like, like that of a Ganoid.

Allied to the Osteoglossidæ is Phareodus (Dapedoglossus), a group of large shad-like fossil fishes, with large scales of peculiar mosaic texture and with a bony casque on the head, found in fresh-water deposits of the Green River Eocene. In the perfect specimens of Phareodus (or Dapedoglossus) testis the first ray of the pectoral is much enlarged and serrated on its inner edge, a character which may separate these fishes as a family from the true Osteoglossidæ. It does not, however, appear in Cope's figures, none of his specimens having the pectorals perfect. In these fishes the teeth are very strong and sharp, the scales are very large and thin, looking like the scales of a parrot-fish, the long dorsal is opposite to the anal and similar to it, and the caudal is truncate. The end of the vertebral column is turned upward.

57Other species are Phareodus acutus, known from the jaws; P. encaustus is known from a mass of thick scales with reticulate or mosaic-like surface, much as in Osteoglossum, and P. æquipennis from a small example, perhaps immature. Phareodus testis is frequently found well preserved in the shales at Fossil Station, to the northwestward of Green River. Whether all these species possess the peculiar structure of the scales, and whether all belong to one genus, is uncertain.

Fig. 45.—Phareodus testis (Cope). From a specimen 20 inches long collected at Fossil, Wyo., in the Museum of the Univ. of Wyoming. (Photograph by Prof. Wilbur C. Knight.)

In Eocene shales of England occurs Brychætus muelleri, a species closely related to Phareodus, but the scales smaller and without the characteristic reticulate or mosaic structure seen in Phareodus encaustus.

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Fig. 46.—Deposits of Green River Shales, bearing Phareodus, at Fossil, Wyoming. (Photograph by Wilbur C. Knight.)

59

Fig. 47.—A day's catch of Fossil fishes, Phareodus, Diplomystus, etc. Green River Eocene Shales, Fossil, Wyoming. (Photograph by Prof. Wilbur C. Knight.)

60The Pantodontidæ.—The bony casque of Osteoglossum is found again in the Pantodontidæ, consisting of one species, Pantodon buchholzi, a small fish of the brooks of West Africa. As in the Osteoglossidæ and in the Siluridæ, the subopercle is wanting in Pantodon.

Fig. 48.—Alepocephalus agassizii Goode & Bean. Gulf Stream.

The Alepocephalidæ are deep-sea herring-like fishes very soft in texture and black in color, taken in the oceanic abysses. Some species may be found in almost all seas below the depth of half a mile. Alepocephalus rostratus of the Mediterranean has been long known, but most of the other genera, Talismania, Mitchillina, Conocara, etc., are of very recent discovery, having been brought to the surface by the deep-sea dredging of the Challenger, the Albatross, the Blake, the Travailleur, the Talisman, the Investigator, the Hirondelle, and the Violante.

The Salmon Family.—The series or suborder Salmonoidea, or allies of the salmon and trout, are characterized as a whole by the presence of the adipose fin, a structure also retained in Characins and catfishes, which have no evident affinity with the trout, and in the lantern-fishes, lizard-fishes, and trout-perches, in which the affinity is very remote. Probably these groups all have a common descent from some primitive fish having an adipose fin, or at least a fleshy fold on the back.

Of all the families of fishes, the one most interesting from almost every point of view is that of the Salmonidæ, the salmon family. As now restricted, it is not one of the largest families, as it comprises less than a hundred species; but in beauty, activity, gaminess, quality as food, and even in size of individuals, different members of the group stand easily with the first among fishes. The following are the chief external characteristics which are common to the members of the family:

Body oblong or moderately elongate, covered with cycloid, in scales of varying size. Head naked. Mouth terminal or somewhat inferior, varying considerably among the different species, those having the mouth largest usually having also the strongest teeth. Maxillary provided with a supplemental bone, and forming the lateral margin of the upper jaw. Pseudobranchiæ present. Gill-rakers varying with the species. Opercula complete. No barbels. Dorsal fin of moderate length, placed near the middle of the length of the body. Adipose fin well developed. Caudal fin forked. Anal fin moderate or rather long. Ventral fins nearly median in position. Pectoral fins inserted low. Lateral line present. Outline of belly rounded. Vertebræ in large number, usually about sixty.

62The stomach in all the Salmonidæ is siphonal, and at the pylorus are many (15 to 200) comparatively large pyloric cœca. The air-bladder is large. The eggs are usually much larger than in fishes generally, and the ovaries are without special duct, the ova falling into the cavity of the abdomen before exclusion. The large size of the eggs, their lack of adhesiveness, and the readiness with which they may be impregnated, render the Salmonidæ peculiarly adapted for artificial culture.

The Salmonidæ are peculiar to the north temperate and Arctic regions, and within this range they are almost equally abundant wherever suitable waters occur. Some of the species, especially the larger ones, are marine and anadromous, living and growing in the sea, and ascending fresh waters to spawn. Still others live in running brooks, entering lakes or the sea when occasion serves, but not habitually doing so. Still others are lake fishes, approaching the shore or entering brooks in the spawning season, at other times retiring to waters of considerable depth. Some of them are active, voracious, and gamy, while others are comparatively defenseless and will not take the hook. They are divisible into ten easily recognized genera: Coregonus, Argyrosomus, Brachymystax, Stenodus, Oncorhynchus, Salmo, Hucho, Cristivomer, Salvelinus, and Plecoglossus.

Fragments of fossil trout, very imperfectly known, are recorded chiefly from Pleistocene deposits of Idaho, under the name of Rhabdofario lacustris. We have also received from Dr. John C. Merriam, from ferruginous sands of the same region, several fragments of jaws of salmon, in the hook-nosed condition, with enlarged teeth, showing that the present salmon-runs have been in operation for many thousands of years. Most other fragments hitherto referred to Salmonidæ belong to some other kind of fish.

Coregonus, the Whitefish.—The genus Coregonus, which includes the various species known in America as lake whitefish, is distinguishable in general by the small size of its mouth, the weakness of its teeth, and the large size of its scales. The teeth, especially, are either reduced to slight asperities, or else are altogether wanting. The species reach a length of one to three feet. With scarcely an exception they inhabit clear lakes, 63and rarely enter streams except to spawn. In far northern regions they often descend to the sea; but in the latitude of the United States this is never possible for them, as they are unable to endure warm or impure water. They seldom take the hook, and rarely feed on other fishes. Numerous local varieties characterize the lakes of Scandinavia, Scotland, and Arctic Asia and America. Largest and most desirable of all these as a food-fish is the common whitefish of the Great Lakes (Coregonus clupeiformis), with its allies or variants in the Mackenzie and Yukon.

The species of Coregonus differ from each other in the form and size of the mouth, in the form of the body, and in the development of the gill-rakers.

Coregonus oxyrhynchus—the Schnäbel of Holland, Germany, and Scandinavia—has the mouth very small, the sharp snout projecting far beyond it. No species similar to this is found in America.

The Rocky Mountain whitefish (Coregonus williamsoni) has also a small mouth and projecting snout, but the latter is blunter and much shorter than in C. oxyrhynchus. This is a small species abounding everywhere in the clear lakes and streams of the Rocky Mountains and the Sierra Nevada, from Colorado to Vancouver Island. It is a handsome fish and excellent as food.

Fig. 49.—Rocky Mountain Whitefish, Coregonus williamsoni Girard.

Closely allied to Coregonus williamsoni is the pilot-fish, shad-waiter, roundfish, or Menomonee whitefish (Coregonus quadrilateralis). This species is found in the Great Lakes, the Adirondack region, the lakes of New Hampshire, and thence 64northwestward to the Yukon, abounding in cold deep waters, its range apparently nowhere coinciding with that of Coregonus williamsoni.

Fig. 50.—Whitefish, Coregonus clupeiformis Mitchill. Ecorse, Mich.

The common whitefish (Coregonus clupeiformis) is the largest in size of the species of Coregonus, and is unquestionably the finest as an article of food. It varies considerably in appearance with age and condition, but in general it is proportionately much deeper than any of the other small-mouthed Coregoni. The adult fishes develop a considerable fleshy hump at the shoulders, which causes the head, which is very small, to appear disproportionately so. The whitefish spawns in November and December, on rocky shoals in the Great Lakes. Its food was ascertained by Dr. P. R. Hoy to consist chiefly of deep-water crustaceans, with a few mollusks, and larvæ of water insects. "The whitefish," writes Mr. James W. Milner, "has been known since the time of the earliest explorers as preeminently a fine-flavored fish. In fact there are few table-fishes its equal. To be appreciated in its fullest excellence it should be taken fresh from the lake and broiled. Father Marquette, Charlevoix, Sir John Richardson—explorers who for months at a time had to depend upon the whitefish for their staple article of food—bore testimony to the fact that they never lost their relish for it, and deemed it a special excellence that the appetite never became cloyed with it." The range of the whitefish extends from the lakes of New York and New England northward to the Arctic Circle. The "Otsego bass" of Otsego 65Lake in New York, celebrated by De Witt Clinton, is a local form of the ordinary whitefish.

Allied to the American whitefish, but smaller in size, is the Lavaret, Weissfisch, Adelfisch, or Weissfelchen (Coregonus lavaretus), of the mountain lakes of Switzerland, Germany, and Sweden. Coregonus kennicotti, the muksun, and Coregonus nelsoni, the humpback whitefish, are found in northern Alaska and in the Yukon. Several other related species occur in northern Europe and Siberia.

Another American species is the Sault whitefish, Lake Whiting or Musquaw River whitefish (Coregonus labradoricus). Its teeth are stronger, especially on the tongue, than in any of our other species, and its body is slenderer than that of the whitefish. It is found in the upper Great Lakes, in the Adirondack region, in Lake Winnipeseogee, and in the lakes of Maine and New Brunswick. It is said to rise to the fly in the Canadian lakes. This species runs up the St. Mary's River, from Lake Huron to Lake Superior, in July and August. Great numbers are snared or speared by the Indians at this season at the Sault Ste. Marie.

In the breeding season the scales are sometimes thickened or covered with small warts, as in the male Cyprinidæ.

Argyrosomus, the Lake Herring.—In the genus Argyrosomus the mouth is larger, the premaxillary not set vertical, but extending forward on its lower edge, and the body is more elongate and more evenly elliptical. The species are more active and predaceous than those of Coregonus and are, on the whole, inferior as food.

The smallest and handsomest of the American whitefish is the cisco of Lake Michigan (Argyrosomus hoyi). It is a slender fish, rarely exceeding ten inches in length, and its scales have the brilliant silvery luster of the mooneye and the ladyfish.

The lake herring, or cisco (Argyrosomus artedi), is, next to the whitefish, the most important of the American species. It is more elongate than the others, and has a comparatively large mouth, with projecting under-jaw. It is correspondingly more voracious, and often takes the hook. During the spawning season of the whitefish the lake herring feeds on the ova of the latter, thereby doing a great amount of mischief. As food 66this species is fair, but much inferior to the whitefish. Its geographical distribution is essentially the same, but to a greater degree it frequents shoal waters. In the small lakes around Lake Michigan, in Indiana and Wisconsin (Tippecanoe, Geneva, Oconomowoc, etc.), the cisco has long been established; and in these waters its habits have undergone some change, as has also its external appearance. It has been recorded as a distinct species, Argyrosomus sisco, and its excellence as a game-fish has been long appreciated by the angler. These lake ciscoes remain for most of the year in the depths of the lake, coming to the surface only in search of certain insects, and to shallow water only in the spawning season. This periodical disappearance of the cisco has led to much foolish discussion as to the probability of their returning by an underground passage to Lake Michigan during the periods of their absence. One author, confounding "cisco" with "siscowet," has assumed that this underground passage leads to Lake Superior, and that the cisco is identical with the fat lake trout which bears the latter name. The name "lake herring" alludes to the superficial resemblance which this species possesses to the marine herring, a fish of quite a different family.

Fig. 51.—Bluefin Cisco, Argyrosomus nigripinnis Gill. Sheboygan.

Closely allied to the lake herring is the bluefin of Lake Michigan and of certain lakes in New York (Argyrosomus nigripinnis), a fine large species inhabiting deep waters, and recognizable by the blue-black color of its lower fins. In the lakes of central New York are found two other species, the so-called lake smelt (Argyrosomus osmeriformis) and the long-jaw (Argyrosomus 67prognathus). Argyrosomus lucidus is abundant in Great Bear Lake. In Alaska and Siberia are still other species of the cisco type (Argyrosomus laurettæ, A. pusillus, A. alascanus); and in Europe very similar species are the Scotch vendace (Argyrosomus vandesius) and the Scandinavian Lok-Sild (lake herring), as well as others less perfectly known.

The Tullibee, or "mongrel whitefish" (Argyrosomus tullibee), has a deep body, like the shad, with the large mouth of the ciscoes. It is found in the Great Lake region and northward, and very little is known of its habits. A similar species (Argyrosomus cyprinoides) is recorded from Siberia—a region which is peculiarly suited for the growth of the Coregoni, but in which the species have never received much study.

Brachymystax and Stenodus, the Inconnus.—Another little-known form, intermediate between the whitefish and the salmon, is Brachymystax lenock, a large fish of the mountain streams of Siberia. Only the skins brought home by Pallas a century ago are yet known. According to Pallas, it sometimes reaches a weight of eighty pounds.

Fig. 52.—Inconnu, Stenodus mackenziei (Richardson). Nulato, Alaska.

Still another genus, intermediate between the whitefish and the salmon, is Stenodus, distinguished by its elongate body, feeble teeth, and projecting lower jaw. The Inconnu, or Mackenzie River salmon, known on the Yukon as "charr" (Stenodus mackenziei), belongs to this genus. It reaches a weight of twenty pounds or more, and in the far north is a food-fish of good quality. It runs in the Yukon as far as White Horse Rapids. Not much is recorded of its habits, and few specimens exist in 68museums. A species of Stenodus called Stenodus leucichthys inhabits the Volga, Obi, Lena, and other northern rivers; but as yet little is definitely known of the species.

Oncorhynchus, the Quinnat Salmon.—The genus Oncorhynchus contains the salmon of the Pacific. They are in fact, as well as in name, the king salmon. The genus is closely related to Salmo, with which it agrees in general as to the structure of its vomer, and from which it differs in the increased number of anal rays, branchiostegals, pyloric cœca, and gill-rakers. The character most convenient for distinguishing Oncorhynchus, young or old, from all the species of Salmo, is the number of developed rays in the anal fin. These in Oncorhynchus are thirteen to twenty, in Salmo nine to twelve.

The species of Oncorhynchus have long been known as anadromous salmon, confined to the North Pacific. The species were first made known nearly one hundred and fifty years ago by that most exact of early observers, Steller, who, almost simultaneously with Krascheninnikov, another early investigator, described and distinguished them with perfect accuracy under their Russian vernacular names. These Russian names were, in 1792, adopted by Walbaum as specific names in giving to these animals a scientific nomenclature. Five species of Oncorhynchus are well known on both shores of the North Pacific, besides one other in Japan. These have been greatly misunderstood by early observers on account of the extraordinary changes due to differences in surroundings, in sex, and in age, and in conditions connected with the process of reproduction.

There are five species of salmon (Oncorhynchus) in the waters of the North Pacific, all found on both sides, besides one other which is known only from the waters of Japan. These species may be called: (1) the quinnat, or king-salmon, (2) the blue-back salmon, or redfish, (3) the silver salmon, (4) the dog-salmon, (5) the humpback salmon, and (6) the masu; or (1) Oncorhynchus tschawytscha, (2) Oncorhynchus nerka, (3) Oncorhynchus milktschitsch, (4) Oncorhynchus keta, (5) Oncorhynchus gorbuscha, (6) Oncorhynchus masou. All these species save the last are now known to occur in the waters of Kamchatka, as well as in those of Alaska and Oregon. These species, in all their varied conditions, may usually be distinguished by the 69characters given below. Other differences of form, color, and appearance are absolutely valueless for distinction, unless specimens of the same age, sex, and condition are compared.

The quinnat salmon (Oncorhynchus tschawytscha),^[7] called quinnat, tyee, chinook, or king-salmon, has an average weight of 22 pounds, but individuals weighing 70 to 100 pounds are occasionally taken. It has about 16 anal rays, 15 to 19 branchiostegals, 23 (9 + 14) gill-rakers on the anterior gill-arch, and 140 to 185 pyloric cœca. The scales are comparatively large, there being from 130 to 155 in a longitudinal series. In the spring the body is silvery, the back, dorsal fin, and caudal fin having more or less of round black spots, and the sides of the head having a peculiar tin-colored metallic luster. In the fall the color is often black or dirty red, and the species can then be distinguished from the dog-salmon by its larger size and by its technical characters. The flesh is rich and salmon-red, becoming suddenly pale as the spawning season draws near.

Fig. 53.—Quinnat Salmon (female), Oncorhynchus tschawytscha (Walbaum). Columbia River.

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Fig. 54.—King-salmon grilse, Oncorhynchus tschawytscha (Walbaum). (Photograph by Cloudsley Rutter.)

Fig. 55.—Male Red Salmon in September, Oncorhynchus nerka (Walbaum). Payette Lake, Idaho.

The blue-back salmon (Oncorhynchus nerka),^[8] also called red salmon, sukkegh, or sockeye, usually weighs from 5 to 8 pounds. It has about 14 developed anal rays, 14 branchiostegals, and 75 to 95 pyloric cœca. The gill-rakers are more numerous than in any other salmon, the number being usually about 39 (16 + 23). The scales are larger, there being 130 to 140 in the lateral line. In the spring the form is plumply rounded, and the color is a clear bright blue above, silvery below, and everywhere immaculate. Young fishes often show a few round black spots, which disappear when they enter the sea. Fall specimens in the lakes are bright crimson in color, the head clear olive-green, and they become in a high degree hook-nosed and slab-sided, and bear little resemblance to the spring run. Young spawning male grilse follow the changes which take place in the adult, although often not more than half a pound in weight. These little fishes often appear in mountain lakes, but whether they are landlocked or have come up from the sea is still unsettled. 71These dwarf forms, called kokos by the Indians and benimasu in Japan, form the subspecies Oncorhynchus nerka kennerlyi. The flesh in this species is firmer than that of any other and very red, of good flavor, though drier and less rich than the king-salmon.

The silver salmon, or coho (Oncorhynchus milktschitsch, or kisutch), reaches a weight of 5 to 8 pounds. It has 13 developed rays in the anal, 13 branchiostegals, 23 (10 + 13) gill-rakers, and 45 to 80 pyloric cœca. There are about 127 scales in the lateral line. The scales are thin and all except those of the lateral line readily fall off. This feature distinguishes the species readily from the red salmon. In color it is silvery in spring, greenish above, and with a few faint black spots on the upper parts only. In the fall the males are mostly of a dirty red. The flesh in this species is of excellent flavor, but pale in color, and hence less valued than that of the quinnat and the red salmon.

The dog-salmon, calico salmon, or chum, called saké in Japan (Oncorhynchus keta), reaches an average weight of about 7 to 10 pounds. It has about 14 anal rays, 14 branchiostegals, 24 (9 + 15) gill-rakers, and 140 to 185 pyloric cœca. There are about 150 scales in the lateral line. In spring it is dirty silvery, immaculate, or sprinkled with small black specks, the fins dusky, the sides with faint traces of gridiron-like bars. In the fall the male is brick-red or blackish, and its jaws are greatly distorted. The pale flesh is well flavored when fresh, but pale and mushy in texture and muddy in taste when canned. It is said to take salt well, and great numbers of salt dog-salmon are consumed in Japan.

The humpback salmon, or pink salmon (Oncorhynchus gorbuscha), is the smallest of the American species, weighing from 3 to 5 pounds. It has usually 15 anal rays, 12 branchiostegals, 28 (13 + 15) gill-rakers, and about 180 pyloric cœca. Its scales are much smaller than in any other salmon, there being 180 to 240 in the lateral line. In color it is bluish above, silvery below, the posterior and upper parts with many round black spots, the caudal fin always having a few large black spots oblong in form. The males in fall are dirty red, and are more extravagantly distorted than in any other of the Salmonidæ. 72The flesh is softer than in the other species; it is pale in color, and, while of fair flavor when fresh, is distinctly inferior when canned.

Fig. 56.—Humpback Salmon (female), Oncorhynchus gorbuscha (Walbaum). Cook's Inlet.

The masu, or yezomasu (Oncorhynchus masou), is very similar to the humpback, the scales a little larger, the caudal without black spots, the back usually immaculate. It is one of the smaller salmon, and is fairly abundant in the streams of Hokkaido, the island formerly known as Yezo.

Fig 57.—Masu (female), Oncorhynchus masou (Brevoort). Aomori, Japan.

Of these species the blue-back or red salmon predominates in Frazer River and in most of the small rivers of Alaska, including all those which flow from lakes. The greatest salmon rivers of the world are the Nushegak and Karluk in Alaska, with the Columbia River, Frazer River, and Sacramento River farther south. The red and the silver salmon predominate in Puget Sound, the quinnat in the Columbia and the Sacramento, and the silver salmon in most of the smaller streams along the coast. All the species occur, however, from the Columbia northward; 73but the blue-back is not found in the Sacramento. Only the quinnat and the dog-salmon have been noticed south of San Francisco. In Japan keta is by far the most abundant species of salmon. It is known as saké, and largely salted and sold in the markets. Nerka is known in Japan only as landlocked in Lake Akan in northern Hokkaido. Milktschitsch is generally common, and with masou is known as masu, or small salmon, as distinguished from the large salmon, or saké. Tschawytscha and gorbuscha are unknown in Japan. Masou has not been found elsewhere.

The quinnat and blue-back salmon, the "noble salmon," habitually "run" in the spring, the others in the fall. The usual order of running in the rivers is as follows: tschawytscha, nerka, milktschitsch, gorbuscha, keta. Those which run first go farthest. In the Yukon the quinnat runs as far as Caribou Crossing and Lake Bennett, 2250 miles. The red salmon runs to "Forty-Mile," which is nearly 1800 miles. Both ascend to the head of the Columbia, Fraser, Nass, Skeena, Stikeen, and Taku rivers. The quinnat runs practically only in the streams of large size, fed with melting snows; the red salmon only in streams which pass through lakes. It spawns only in small streams at the head of a lake. The other species spawn in almost any fresh water and only close to the sea.

The economic value of the spring-running salmon is far greater than that of the other species, because they can be captured in numbers when at their best, while the others are usually taken only after deterioration.

The habits of the salmon in the ocean are not easily studied. Quinnat and silver salmon of all sizes are taken with the seine at almost any season in Puget Sound and among the islands of Alaska. This would indicate that these species do not go far from the shore. The silver salmon certainly does not. The quinnat pursues the schools of herring. It takes the hook freely in Monterey Bay, both near the shore and at a distance of six to eight miles out. We have reason to believe that these two species do not necessarily seek great depths, but probably remain not very far from the mouth of the rivers in which they were spawned. The blue-back or red salmon certainly seeks deeper water, as it is seldom or never taken with the seine along shore, and it is known to enter the Strait of Fuca in 74July, just before the running season, therefore coming in from the open sea. The great majority of the quinnat salmon, and probably all the blue-back salmon, enter the rivers in the spring. The run of the quinnat begins generally at the last of March; it lasts, with various modifications and interruptions, until the actual spawning season in November, the greatest run being in early June in Alaska, in July in the Columbia. The run begins earliest in the northernmost rivers, and in the longest streams, the time of running and the proportionate amount in each of the subordinate runs varying with each different river. In general the runs are slack in the summer and increase with the first high water of autumn. By the last of August only straggling blue-backs can be found in the lower course of any stream; but both in the Columbia and in the Sacramento the quinnat runs in considerable numbers at least till October. In the Sacramento the run is greatest in the fall, and more run in the summer than in spring. In the Sacramento and the smaller rivers southward there is a winter run, beginning in December. The spring quinnat salmon ascends only those rivers which are fed by the melting snows from the mountains and which have sufficient volume to send their waters well out to sea. Those salmon which run in the spring are chiefly adults (supposed to be at least three years old). Their milt and spawn are no more developed than at the same time in others of the same species which have not yet entered the rivers. It would appear that the contact with cold fresh water, when in the ocean, in some way causes them to run towards it, and to run before there is any special influence to that end exerted by the development of the organs of generation. High water on any of these rivers in the spring is always followed by an increased run of salmon. The salmon-canners think—and this is probably true—that salmon which would not have run till later are brought up by the contact with the cold water. The cause of this effect of cold fresh water is not understood. We may call it an instinct of the salmon, which is another way of expressing our ignorance. In general it seems to be true that in those rivers and during those years when the spring run is greatest the fall run is least to be depended on.

The blue-back salmon runs chiefly in July and early August, 75beginning in late June in Chilcoot River, where some were found actually spawning July 15; beginning after the middle of July in Frazer River.

As the season advances, smaller and younger salmon of these species (quinnat and blue-back) enter the rivers to spawn, and in the fall these young specimens are very numerous. We have thus far failed to notice any gradations in size or appearance of these young fish by which their ages could be ascertained. It is, however, probable that some of both sexes reproduce at the age of one year. In Frazer River, in the fall, quinnat male grilse of every size, from eight inches upwards, were running, the milt fully developed, but usually not showing the hooked jaws and dark colors of the older males. Females less than eighteen inches in length were not seen. All of either sex, large and small, then in the river had the ovaries or milt developed. Little blue-backs of every size, down to six inches, are also found in the upper Columbia in the fall, with their organs of generation fully developed. Nineteen-twentieths of these young fish are males, and some of them have the hooked jaws and red color of the old males. Apparently all these young fishes, like the old ones, die after spawning.

The average weight of the adult quinnat in the Columbia, in the spring, is twenty-two pounds; in the Sacramento, about sixteen. Individuals weighing from forty to sixty pounds are frequently found in both rivers, and some as high as eighty or even one hundred pounds are recorded, especially in Alaska, where the species tends to run larger. It is questionable whether these large fishes are those which, of the same age, have grown more rapidly; those which are older, but have for some reason failed to spawn; or those which have survived one or more spawning seasons. All these origins may be possible in individual cases. There is, however, no positive evidence that any salmon of the Pacific survives the spawning season.

Those fish which enter the rivers in the spring continue their ascent till death or the spawning season overtakes them. Doubtless not one of them ever returns to the ocean, and a large proportion fail to spawn. They are known to ascend the Sacramento to its extreme head-waters, about four hundred miles. In the Columbia they ascend as far as the Bitter Root and Sawtooth 76mountains of Idaho, and their extreme limit is not known. This is a distance of nearly a thousand miles. In the Yukon a few ascend to Caribou Crossing and Lake Bennett, 2250 miles. At these great distances, when the fish have reached the spawning grounds, besides the usual changes of the breeding season their bodies are covered with bruises, on which patches of white fungus (Saprolegnia) develop. The fins become mutilated, their eyes are often injured or destroyed, parasitic worms gather in their gills, they become extremely emaciated, their flesh becomes white from the loss of oil; and as soon as the spawning act is accomplished, and sometimes before, all of them die. The ascent of the Cascades and the Dalles of the Columbia causes the injury or death of a great many salmon.

Fig. 58.—Red Salmon (mutilated dwarf male, after spawning), Oncorhynchus nerka (Walbaum). Alturas Lake, Idaho.

When the salmon enter the river they refuse to take bait, and their stomachs are always found empty and contracted. In the rivers they do not feed; and when they reach the spawning grounds their stomachs, pyloric cœca and all, are said to be no larger than one's finger. They will sometimes take the fly, or a hook baited with salmon-roe, in the clear waters of the upper tributaries, but this is apparently solely out of annoyance, snapping at the meddling line. Only the quinnat and blue-back (there called redfish) have been found at any great distance from the sea, and these (as adult fishes) only in late summer and fall.

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Fig. 59.—Young Male Quinnat Salmon, Oncorhynchus tschawytscha, dying after spawning. Sacramento River. (Photograph by Cloudsley Rutter.)

78The spawning season is probably about the same for all the species. It varies for each of the different rivers, and for different parts of the same river. It doubtless extends from July to December, and takes place usually as soon as the temperature of the water falls to 54°. The manner of spawning is probably similar for all the species. In the quinnat the fishes pair off; the male, with tail and snout, excavates a broad, shallow "nest" in the gravelly bed of the stream, in rapid water, at a depth of one to four feet and the female deposits her eggs in it. They then float down the stream tail foremost, the only fashion in which salmon descend to the sea. As already stated, in the head-waters of the large streams, unquestionably, all die; it is the belief of the writer that none ever survive. The young hatch in sixty days, and most of them return to the ocean during the high water of the spring. They enter the river as adults at the age of about four years.

The salmon of all kinds in the spring are silvery, spotted or not according to the species, and with the mouth about equally symmetrical in both sexes. As the spawning season approaches the female loses her silvery color, becomes more slimy, the scales on the back partly sink into the skin, and the flesh changes from salmon-red and becomes variously paler, from the loss of oil; the degree of paleness varying much with individuals and with inhabitants of different rivers. In the Sacramento the flesh of the quinnat, in either spring or fall, is rarely pale. In the Columbia a few with pale flesh are sometimes taken in spring, and an increasing number from July on. In Frazer River the fall run of the quinnat is nearly worthless for canning purposes, because so many are "white-meated." In the spring very few are "white-meated"; but the number increases towards fall, when there is every variation, some having red streaks running through them, others being red toward the head and pale toward the tail. The red and pale ones cannot be distinguished externally, and the color is dependent on neither age nor sex. There is said to be no difference in the taste, but there is little market for canned salmon not of the conventional orange-color.

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Fig. 60.—Quinnat Salmon, Oncorhynchus tschawytscha (Walbaum). Monterey Bay. (Photograph by C. Rutter.)

As the season advances the difference between the males and females becomes more and more marked, and keeps pace with the development of the milt, as is shown by dissection. The males have (1) the premaxillaries and the tip of the lower jaw more and more prolonged, both of the jaws becoming finally strongly and often extravagantly hooked, so that either they shut by the side of each other like shears, or else the mouth cannot be closed. (2) The front teeth become very long and canine-like, their growth proceeding very rapidly, until they are often half an inch long. (3) The teeth on the vomer and tongue often disappear. (4) The body grows more compressed and deeper at the shoulders, so that a very distinct hump is formed; this is more developed in the humpback salmon, but is found in all. (5) The scales disappear, especially on the back, by the growth of spongy skin. (6) The color changes from silvery to various shades of black and red, or blotchy, according to the species. The blue-back turns rosy-red, the head bright olive; the dog-salmon a dull red with blackish bars, and the quinnat generally blackish. The distorted males are commonly considered worthless, rejected by the canners and salmon-salters, but preserved by the Indians. These changes are due solely to influences connected with the growth of the reproductive organs. They are not in any way due to the action of fresh water. They take place at about the same time in the adult males of all species, whether in the ocean or in the rivers. At the time of the spring runs all are symmetrical. In the fall all males, of whatever species, are more or less distorted. Among the dog-salmon, which run only in the fall, the males are hook-jawed and red-blotched when they first enter the Strait of Fuca from the outside. The humpback, taken in salt water about Seattle, have the same peculiarities. The male is slab-sided, hook-billed, and distorted, and is rejected 80by the canners. No hook-jawed females of any species have been seen.

On first entering a stream the salmon swim about as if playing. They always head towards the current, and this appearance of playing may be simply due to facing the moving tide. Afterwards they enter the deepest parts of the stream and swim straight up, with few interruptions. Their rate of travel at Sacramento is estimated by Stone at about two miles per day; on the Columbia at about three miles per day. Those which enter the Columbia in the spring and ascend to the mountain rivers of Idaho must go at a more rapid rate than this, as they must make an average of nearly four miles per day.

As already stated, the economic value of any species depends in great part on its being a "spring salmon." It is not generally possible to capture salmon of any species in large numbers until they have entered the estuaries or rivers, and the spring salmon enter the large rivers long before the growth of the organs of reproduction has reduced the richness of the flesh. The fall salmon cannot be taken in quantity until their flesh has deteriorated; hence the dog-salmon is practically almost worthless except to the Indians, and the humpback salmon was regarded as little better until comparatively recently, when it has been placed on the market in cans as "Pink Salmon." It sells for about half the price of the red salmon and one-third that of the quinnat. The red salmon is smaller than the quinnat but, outside the Sacramento and the Columbia, far more abundant, and at present it exceeds the quinnat in economic value. The pack of red salmon in Alaska amounted in 1902 to over two million cases (48 pounds each), worth wholesale about $4.00 per case, or about $8,000,000. The other species in Alaska yield about one million cases, the total wholesale value of the pack for 1902 being $8,667,673. The aggregate value of the quinnat is considerably less, but either species far exceed in value all other fishes of the Pacific taken together. The silver salmon is found in the inland waters of Puget Sound for a considerable time before the fall rains cause the fall runs, and it may be taken in large numbers with seines before the season for entering the rivers.

The fall salmon of all species, but especially of the dog-salmon, 81ascend streams but a short distance before spawning. They seem to be in great anxiety to find fresh water, and many of them work their way up little brooks only a few inches deep, where they perish miserably, floundering about on the stones. Every stream of whatever kind, from San Francisco to Bering Sea, has more or less of these fall salmon.

The absence of the fine spring salmon in the streams of Japan is the cause of the relative unimportance of the river fisheries of the northern island of Japan, Hokkaido. It is not likely that either the quinnat or the red salmon can be introduced into these rivers, as they have no snow-fed streams, and few of them pass through lakes which are not shut off by waterfalls. For the same reason neither of these species is likely to become naturalized in the waters of our Eastern States, though it is worth while to bring the red salmon to the St. Lawrence. The silver salmon, already abundant in Japan, should thrive in the rivers and bays of New England.

The Parent-stream Theory.—It has been generally accepted as unquestioned by packers and fishermen that salmon return to spawn to the very stream in which they were hatched. As early as 1880 the present writer placed on record his opinion that this theory was unsound. In a general way most salmon return to the parent stream, because when in the sea the parent stream is the one most easily reached. The channels and runways which directed their course to the sea may influence their return trip in the same fashion. When the salmon is mature it seeks fresh water. Other things being equal, about the same number will run each year in the same channel. With all this, we find some curious facts. Certain streams will have a run of exceptionally large or exceptionally small red salmon. The time of the run bears some relation to the length of the stream: those who have farthest to go start earliest. The time of running bears also a relation to the temperature of the spawning grounds: where the waters cool off earliest the fish run soonest.

The supposed evidence in favor of the parent-stream theory may be considered under three heads:^[9] (1) Distinctive runs in 82various streams. (2) Return of marked salmon. (3) Introduction of salmon into new streams followed by their return.

Under the first head it is often asserted of fishermen that they can distinguish the salmon of different streams. Thus the Lynn Canal red salmon are larger than those in most waters, and it is claimed that those of Chilcoot Inlet are larger than those of the sister stream at Chilcat. The red salmon of Red Fish Bay on Baranof Island are said to be much smaller than usual, and those of the neighboring Necker Bay are not more than one-third the ordinary size. Those of a small rapid stream near Nass River are more wiry than those of the neighboring large stream. The same claim is made for the different streams of Puget Sound, each one having its characteristic run. In all this there is some truth and perhaps some exaggeration. I have noticed that the Chilcoot fish seem deeper in body than those at Chilcat. The red salmon becomes compressed before spawning, and the Chilcoot fishes having a short run spawn earlier than the Chilcat fishes, which have many miles to go, the water being perhaps warmer at the mouth of the river. Perhaps some localities may meet the nervous reactions of small fishes, while not attracting the large ones. Mr. H. S. Davis well observes that "until a constant difference has been demonstrated by a careful examination of large numbers of fish from each stream taken at the same time, but little weight can be attached to arguments of this nature."

It is doubtless true as a general proposition that nearly all salmon return to the region in which they were spawned. Most of them apparently never go far away from the mouth of the stream or the bay into which it flows. It is true that salmon are occasionally taken well out at sea, and it is certain that the red salmon runs of Puget Sound come from outside the Straits of Fuca. There is, however, evidence that they rarely go so far as that. When seeking shore they do not reach the original channels.

In 1880 the writer, studying the salmon of the Columbia, used the following words, which he has not had occasion to change:

"It is the prevailing impression that the salmon have some special instinct which leads them to return to spawn in the 83same spawning grounds where they were originally hatched. We fail to find any evidence of this in the case of the Pacific-coast salmon, and we do not believe it to be true. It seems more probable that the young salmon hatched in any river mostly remain in the ocean within a radius of twenty, thirty, or forty miles of its mouth. These, in their movements about in the ocean, may come into contact with the cold waters of their parent rivers, or perhaps of any other river, at a considerable distance from the shore. In the case of the quinnat and the blue-back their 'instinct' seems to lead them to ascend these fresh waters, and in a majority of cases these waters will be those in which the fishes in question were originally spawned. Later in the season the growth of the reproductive organs leads them to approach the shore and search for fresh waters, and still the chances are that they may find the original stream. But undoubtedly many fall salmon ascend, or try to ascend, streams in which no salmon was ever hatched. In little brooks about Puget Sound, where the water is not three inches deep, are often found dead or dying salmon which have entered them for the purpose of spawning. It is said of the Russian River and other California rivers that their mouths, in the time of low water in summer, generally become entirely closed by sand-bars, and that the salmon, in their eagerness to ascend them, frequently fling themselves entirely out of water on the beach. But this does not prove that the salmon are guided by a marvelous geographical instinct which leads them to their parent river in spite of the fact that the river cannot be found. The waters of Russian River soak through these sand-bars, and the salmon instinct, we think, leads them merely to search for fresh waters. This matter is much in need of further investigation; at present, however, we find no reason to believe that the salmon enter the Rogue River simply because they were spawned there, or that a salmon hatched in the Clackamas River is more likely, on that account, to return to the Clackamas than to go up the Cowlitz or the Des Chûtes."

Attempts have been made to settle this question by marking the fry. But this is a very difficult matter indeed. Almost the only structure which can be safely mutilated is the adipose fin, and this is often nipped off by sticklebacks and other meddling 84fish. The following experiments have been tried, according to Mr. Davis:

In March, 1896, 5000 king-salmon fry were marked by cutting off the adipose fin, then set free in the Clackamas River. Nearly 400 of these marked fish are said to have been taken in the Columbia in 1898, and a few more in 1899. In addition a few were taken in 1898, 1899, and 1900 in the Sacramento River, but in much less numbers than in the Columbia. In the Columbia most were taken at the mouth of the river, where nearly all of the fishing was done, but a few were in the original stream, the Clackamas. It is stated that the fry thus set free in the Clackamas came from eggs obtained in the Sacramento—a matter which has, however, no bearing on the present case.

In the Kalama hatchery on the Columbia River, Washington, 2000 fry of the quinnat or king-salmon were marked in 1899 by a V-shaped notch in the caudal fin. Numerous fishes thus marked were taken in the lower Columbia in 1901 and 1902. A few were taken at the Kalama hatchery, but some also at the hatcheries on Wind River and Clackamas River. At the hatchery on Chehalis River six or seven were taken, the stream not being a tributary of the Columbia, but flowing into Shoalwater Bay. None were noticed in the Sacramento. The evidence shows that the most who are hatched in a large stream tend to return to it, and that in general most salmon return to the parent region. There is no evidence that a salmon hatched in one branch of a river tends to return there rather than to any other. Experiments of Messrs. Rutter and Spaulding in marking adult fish at Karluk would indicate that they roam rather widely about the island before spawning. An adult spawning fish, marked and set free at Karluk, was taken soon after on the opposite side of the island of Kadiak.

The introduction of salmon into new streams may throw some light on this question. In 1897 and 1898 3,000,000 young quinnat-salmon fry were set free in Papermill Creek near Olema, California. This is a small stream flowing into the head of Tomales Bay, and it had never previously had a run of salmon. In 1900, and especially in 1901, large quinnat salmon appeared in considerable numbers in this stream. One specimen weighing about sixteen pounds was sent to the present writer for 85identification. These fishes certainly returned to the parent stream, although this stream was one not at all fitted for their purpose.

But this may be accounted for by the topography of the bay. Tomales Bay is a long and narrow channel, about twenty miles long and from one to five in width, isolated from other rivers and with but one tributary stream. Probably the salmon had not wandered far from it; some may not have left it at all. In any event, a large number certainly came back to the same place.

That the salmon rarely go far away is fairly attested. Schools of king-salmon play in Monterey Bay, and chase the herring about in the channels of southeastern Alaska. A few years since Captain J. F. Moser, in charge of the Albatross, set gill-nets for salmon at various places in the sea off the Oregon and Washington coast, catching none except in the bays.

Mr. Davis gives an account of the liberation of salmon in Chinook River, which flows into the Columbia at Baker's Bay:

"It is a small, sluggish stream and has never been frequented by Chinook salmon, although considerable numbers of silver and dog salmon enter it late in the fall. A few years ago the State established a hatchery on this stream, and since 1898 between 1,000,000 and 2,000,000 Chinook fry have been turned out here annually. The fish are taken from the pound-nets in Baker's Bay, towed into the river in crates and then liberated above the dike, which prevents their return to the Columbia. When ripe the salmon ascend to the hatchery, some two or three miles farther up the river, where they are spawned.

"The superintendent of the hatchery, Mr. Hansen, informs me that in 1902, during November and December, quite a number of Chinook salmon ascended the Chinook River. About 150 salmon of both sexes were taken in a trap located in the river about four miles from its mouth. At first thought it would appear that these were probably fish which, when fry, had been liberated in the river, but unfortunately there is no proof that this was the case. According to Mr. Hansen, the season of 1902 was remarkable in that the salmon ran inshore in large schools, a thing which they had not done before for years. It 86is possible that the fish, being forced in close to the shore, came in contact with the current from the Chinook River, which, since the stream is small and sluggish, would not be felt far from shore. Once brought under the influence of the current from the river, the salmon would naturally ascend that stream, whether they had been hatched there or not."

The general conclusion, apparently warranted by the facts at hand, is that salmon, for the most part, do not go to a great distance from the stream in which they are hatched, that most of them return to the streams of the same region, a majority to the parent stream, but that there is no evidence that they choose the parental spawning grounds in preference to any other, and none that they will prefer an undesirable stream to a favorable one for the reason that they happen to have been hatched in the former.

The Jadgeska Hatchery.—Mr. John C. Callbreath of Wrangel, Alaska, has long conducted a very interesting but very costly experiment in this line. About 1890 he established himself in a small stream called Jadgeska on the west coast of Etolin Island, tributary to McHenry Inlet, Clarence Straits. This stream led from a lake, and in it a few thousand red salmon spawned, besides multitudes of silver salmon, dog-salmon, and humpback salmon. Making a dam across the stream, he helped the red salmon over it, destroying all of the inferior kinds which entered the stream. He also established a hatchery for the red salmon, turning loose many fry yearly for ten or twelve years. This was done in the expectation that all the salmon hatched would return to Jadgeska in about four years. By destroying all individuals of other species attempting to run, it was expected that they would become extinct so far as the stream is concerned.

The result of this experiment has been disappointment. After twelve years or more there has been no increase of red salmon in the stream, and no decrease of humpbacks and other humbler forms of salmon. Mr. Callbreath draws the conclusion that salmon run at a much greater age than has been supposed—at the age of sixteen years, perhaps, instead of four. A far more probable conclusion is that his salmon have joined other bands bound for more suitable streams. It is indeed 87claimed that since the establishment of Callbreath's hatchery on Etolin Island there has been a notable increase of the salmon run in the various streams of Prince of Wales Island on the opposite side of Clarence Straits. But this statement, while largely current among the cannerymen, and not improbable, needs verification.

We shall await with much interest the return of the thousands of salmon hatched in 1902 in Naha stream. We may venture the prophecy that while a large percentage will return to Loring, many others will enter Yes Bay, Karta Bay, Moira Sound, and other red salmon waters along the line of their return from Dixon Entrance or the open sea.

Salmon-packing.—The canning of salmon, that is, the packing of the flesh in tin cases, hermetically sealed after boiling, was begun on the Columbia River by the Hume Brothers in 1866. In 1874 canneries were established on the Sacramento River, in 1876 on Puget Sound and on Frazer River, and in 1878 in Alaska. At first only the quinnat salmon was packed; afterwards the red salmon and the silver salmon, and finally the humpback, known commercially as pink salmon. In most cases the flesh is packed in one-pound tins, forty-eight of which constitute a case. The wholesale price in 1903 was for quinnat salmon $5.60 per case, red salmon $4.00, silver salmon $2.60, humpback salmon $2.00, and dog-salmon $1.50. It costs in round numbers $2.00 to pack a case of salmon. The very low price of the inferior brands is due to overproduction.

The output of the salmon fishery of the Pacific coast amounts to about fifteen millions per year, that of Alaska constituting seven to nine millions of this amount. Of this amount the red salmon constitutes somewhat more than half, the quinnat about four-fifths of the rest.

In almost all salmon streams there is evidence of considerable diminution in numbers, although the evidence is sometimes conflicting. In Alaska this has been due to the vicious custom, now done away with, of barricading the streams so that the fish could not reach the spawning grounds, but might be all taken with the net. In the Columbia River the reduction in numbers is mainly due to stationary traps and salmon-wheels, which leave the fish relatively little chance to reach the 88spawning grounds. In years of high water doubtless many salmon run in the spring which might otherwise have waited until fall.

The key to the situation lies in the artificial propagation of salmon by means of well-ordered hatcheries. By this means the fisheries of the Sacramento have been fully restored, those of the Columbia approximately maintained, and a hopeful beginning has been made in hatching red salmon in Alaska.

Salmo, the Trout and Atlantic Salmon.—The genus Salmo comprises those forms of salmon which have been longest known. As in related genera, the mouth is large, and the jaws, palatines, and tongue are armed with strong teeth. The vomer is flat, its shaft not depressed below the level of the head or chevron (the anterior end). There are a few teeth on the chevron; and behind it, on the shaft, there is either a double series of teeth or an irregular single series. These teeth in the true salmon disappear with age, but in the others (the black-spotted trout) they are persistent. The scales are silvery and moderate or small in size. There are 9 to 11 developed rays in the anal fin. The caudal fin is truncate, or variously concave or forked. There are usually 40 to 70 pyloric cœca, 11 or 12 branchiostegals, and about 20 (8 + 12) gill-rakers. The sexual peculiarities are in general less marked than in Oncorhynchus; they are also greater in the anadromous species than in those which inhabit fresh waters. In general the male in the breeding season is redder, its jaws are prolonged, the front teeth enlarged, the lower jaw turned upwards at the end, and the upper jaw notched, or sometimes even perforated, by the tip of the lower. All the species of Salmo (like those of Oncorhynchus) are more or less spotted with black. Unlike the species of Oncorhynchus, the species of Salmo feed more or less while in fresh water, and the individuals for the most part do not die after spawning, although many old males do thus perish.

The Atlantic Salmon.—The large species of Salmo, called salmon by English-speaking people (Salmo salar, Salmo trutta), are marine and anadromous, taking the place in the North Atlantic occupied in the North Pacific by the species of Oncorhynchus. 90Two others more or less similar in character occur in Japan and Kamchatka. The others (trout), forming the subgenus Salar, are non-migratory, or at least irregularly or imperfectly anadromous. The true or black-spotted trout abound in all streams of northern Europe, northern Asia, and in that part of North America which lies west of the Mississippi Valley. The black-spotted trout are entirely wanting in eastern America—a remarkable fact in geographical distribution, perhaps explained only on the hypothesis of the comparatively recent and Eurasiatic origin of the group, which, we may suppose, has not yet had opportunity to extend its range across the plains, unsuitable for salmon life, which separate the upper Missouri from the Great Lakes.

The salmon (Salmo salar) is the only black-spotted salmonoid found in American waters tributary to the Atlantic. In Europe, where other species similarly colored occur, the species may be best distinguished by the fact that the teeth on the shaft of the vomer mostly disappear with age. From the only other species positively known, the salmon trout (Salmo trutta), which shares this character, the true salmon may be distinguished by the presence of but eleven scales between the adipose fin and the lateral line, while Salmo trutta has about fourteen. The scales are comparatively large in the salmon, there being about one hundred and twenty-five in the lateral line. The caudal fin, which is forked in the young, becomes, as in other species of salmon, more or less truncate with age. The pyloric cœca are fifty to sixty in number.

The color in adults, according to Dr. Day, is "superiorly of a steel-blue, becoming lighter on the sides and beneath. Mostly a few rounded or X-shaped spots scattered above the lateral line and upper half of the head, being more numerous in the female than in the male. Dorsal, caudal, and pectoral fins dusky; ventrals and anal white, the former grayish internally. Prior to entering fresh waters these fish are of a brilliant steel-blue along the back, which becomes changed to a muddy tinge when they enter rivers. After these fish have passed into the fresh waters for the purpose of breeding, numerous orange streaks appear in the cheeks of the male, and also spots or even marks of the same, and likewise of a red color, on the body. 91It is now termed a 'redfish.' The female, however, is dark in color and known as 'blackfish.' 'Smolts' (young river fish) are bluish along the upper half of the body, silvery along the sides, due to a layer of silvery scales being formed over the trout-like colors, while they have darker fins than the yearling 'ping,' but similar bands and spots, which can be seen (as in the parr) if the example be held in certain positions of light. 'Parr' (fishes of the year) have two or three black spots only on the opercle, and black spots and also orange ones along the upper half of the body, and no dark ones below the lateral line, although there may be orange ones which can be seen in its course. Along the side of the body are a series (12 to 15) of transverse bluish bands, wider than the ground color and crossing the lateral line, while in the upper half of the body the darker color of the back forms an arch over each of these bands, a row of spots along the middle of the rayed dorsal fin, and the adipose orange-tipped."

The dusky cross-shades found in the young salmon or parr are characteristic of the young of salmon, trout, grayling, and nearly all the other Salmonidæ.

The salmon of the Atlantic is, as already stated, an anadromous fish, spending most of its life in the sea, and entering the streams in the fall for the purpose of reproduction. The time of running varies much in different streams and also in different countries. As with the Pacific species, these salmon are not easily discouraged in their progress, leaping cascades and other obstructions, or, if these prove impassable, dying after repeated fruitless attempts.

The young salmon, known as the "parr," is hatched in the spring. It usually remains about two years in the rivers, descending at about the third spring to the sea, when it is known as "smolt." In the sea it grows much more rapidly, and becomes more silvery in color, and is known as "grilse." The grilse rapidly develop into the adult salmon; and some of them, as in the case with the grilse of the Pacific salmon, are capable of reproduction.

After spawning the salmon are very lean and unwholesome in appearance, as in fact. They are then known as "kelts." The Atlantic salmon does not ascend rivers to any such distances 92as those traversed by the quinnat and the blue-back. Its kelts, therefore, for the most part survive the act of spawning. Dr. Day thinks that they feed upon the young salmon in the rivers, and that, therefore, the destruction of the kelts might increase the supply of salmon.

As a food-fish the Atlantic salmon is very similar to the quinnat salmon, neither better nor worse, so far as I can see, when equally fresh. In both the flesh is rich and finely flavored; but the appetite of man becomes cloyed with salmon-flesh sooner than with that of whitefish, smelt, or charr. In size the Atlantic salmon does not fall far short of the quinnat. The average weight of the adult is probably less than fifteen pounds. The largest one of which I find a record was taken on the coast of Ireland in 1881, and weighed 84¾ pounds.

The salmon is found in Europe between the latitude of 45° and 75°. In the United States it is now rarely seen south of Cape Cod, although formerly the Hudson and numerous other rivers were salmon-streams. Overfishing, obstructions in the rivers, and pollution of the water by manufactories and by city sewage are agencies against which the salmon cannot cope.

Seven species of salmon (as distinguished from trout) are recognized by Dr. Günther in Europe, and three in America. The landlocked forms, abundant in Norway, Sweden, and Maine, which cannot, or at least do not, descend to the sea, are regarded by him as distinct species. "The question," observes Dr Günther, "whether any of the migratory species can be retained by artificial means in fresh water, and finally accommodate themselves to a permanent sojourn therein, must be negatived for the present." On this point I think that the balance of evidence leads to a different conclusion. These fresh-water forms (Sebago and Ouananiche) are actually salmon which have become landlocked. I have compared numerous specimens of the common landlocked salmon (Salmo salar sebago) of the lakes of Maine and New Brunswick with landlocked salmon (Salmo salar hardini) from the lakes of Sweden, and with numerous migratory salmon, both from America and Europe. I see no reason for regarding them as specifically distinct. The differences are very trivial in kind, and not greater than would be expected on the hypothesis of recent 93adaptation of the salmon to lake life. We have therefore on our Atlantic coast but one species of salmon, Salmo salar. The landlocked form of the lakes of Maine is Salmo salar sebago. The Ouananiche of Lake St. John and the Saguenay, beloved of anglers, is Salmo salar ouananiche.

The Ouananiche.—Dr. Henry Van Dyke writes thus of the Ouananiche: "But the prince of the pool was the fighting Ouananiche, the little salmon of St. John. Here let me chant thy praise, thou noblest and most high-minded fish, the cleanest feeder, the merriest liver, the loftiest leaper, and the bravest warrior of all creatures that swim! Thy cousin, the trout, in his purple and gold with crimson spots, wears a more splendid armor than thy russet and silver mottled with black, but thine is the kinglier nature.

"The old salmon of the sea who begat thee long ago in these inland waters became a backslider, descending again to the ocean, and grew gross and heavy with coarse feeding. But thou, unsalted salmon of the foaming floods, not landlocked as men call thee, but choosing of thine own free will to dwell on a loftier level in the pure, swift current of a living stream, hath grown in grace and risen to a better life.

"Thou art not to be measured by quantity but by quality, and thy five pounds of pure vigor will outweigh a score of pounds of flesh less vitalized by spirit. Thou feedest on the flies of the air, and thy food is transformed into an aerial passion for flight, as thou springest across the pool, vaulting toward the sky. Thine eyes have grown large and keen by piercing through the foam, and the feathered hook that can deceive thee must be deftly tied and delicately cast. Thy tail and fins, by ceaseless conflict with the rapids, have broadened and strengthened, so that they can flash thy slender body like a living arrow up the fall. As Launcelot among the knights, so art thou among the fish, the plain-armored hero, the sunburnt champion of all the water-folk."

Dr. Francis Day, who has very thoroughly studied these fishes, takes, in his memoir on "The Fishes of Great Britain and Ireland," and in other papers, a similar view in regard to the European species. Omitting the species with permanent teeth on the shaft of the vomer (subgenus Salar), he finds 94among the salmon proper only two species, Salmo salar and Salmo trutta. The latter species, the sea-trout or salmon-trout of England and the estuaries of northern Europe, is similar to the salmon in many respects, but has rather smaller scales, there being fourteen in an oblique series between the adipose fin and the lateral line. It is not so strong a fish as the salmon, nor does it reach so large a size. Although naturally anadromous, like the true salmon, landlocked forms of the salmon-trout are not uncommon. These have been usually regarded as different species, while aberrant or intermediate individuals are usually regarded as hybrids. The salmon-trout of Europe have many analogies with the steelhead of the Pacific.

The present writer has examined many thousands of American Salmonidæ, both of Oncorhynchus and Salmo. While many variations have come to his attention, and he has been compelled more than once to modify his views as to specific distinctions, he has never yet seen an individual which he had the slightest reason to regard as a "hybrid." It is certainly illogical to conclude that every specimen which does not correspond to our closet-formed definition of its species must therefore be a "hybrid" with some other. There is no evidence worth mentioning, known to me, of extensive hybridization in a state of nature in any group of fishes. This matter is much in need of further study; for what is true of the species in one region, in this regard, may not be true of others. Dr. Günther observes:

"Johnson, a correspondent of Willughby, had already expressed his belief that the different salmonoids interbreed; and this view has since been shared by many who have observed these fishes in nature. Hybrids between the sewin (Salmo trutta cambricus) and the river-trout (Salmo fario) were numerous in the Rhymney and other rivers of South Wales before salmonoids were almost exterminated by the pollutions allowed to pass into these streams, and so variable in their characters that the passage from one species to the other could be demonstrated in an almost unbroken series, which might induce some naturalists to regard both species as identical. Abundant evidence of a similar character has accumulated, showing the frequent occurrence of hybrids between Salmo fario and S. trutta.... In some rivers the conditions appear 95to be more favorable to hybridism than in others in which hybrids are of comparatively rare occurrence. Hybrids between the salmon and other species are very scarce everywhere."

Very similar to the European Salmo trutta is the trout of Japan (Salmo perryi), the young called yamabe, the adult kawamasu, or river-salmon. This species abounds everywhere in Japan, the young being the common trout of the brooks, black-spotted and crossed by parr-marks, the adult reaching a weight of ten or twelve pounds in the larger rivers and descending to the sea. In Kamchatka is another large, black-spotted, salmon-like species properly to be called a salmon-trout. This is Salmo mykiss, a name very wrongly applied to the cutthroat trout of the Columbia.

The black-spotted trout, forming the subgenus Salar, differ from Salmo salar and Salmo trutta in the greater development of the vomerine teeth, which are persistent throughout life, in a long double series on the shaft of the vomer. About seven species are laboriously distinguished by Dr. Günther in the waters of western Europe. Most of these are regarded by Dr. Day as varieties of Salmo fario. The latter species, the common river-trout or lake-trout of Europe, is found throughout northern and central Europe, wherever suitable waters occur. It is abundant, gamy, takes the hook readily, and is excellent as food. It is more hardy than the different species of charr, although from an æsthetic point of view it must be regarded as inferior to all of the Salvelini. The largest river-trout recorded by Dr. Day weighed twenty-one pounds. Such large individuals are usually found in lakes in the north, well stocked with smaller fishes on which trout may feed. Farther south, where the surroundings are less favorable to trout-life, they become mature at a length of less than a foot, and a weight of a few ounces. These excessive variations in the size of individuals have received too little notice from students of Salmonidæ. Similar variations occur in all the non-migratory species of Salmo and of Salvelinus. Numerous river-trout have been recorded from northern Asia, but as yet nothing can be definitely stated as to the number of species actually existing.

The Black-spotted Trout.—In North America only the region west of the Mississippi Valley, the streams of southeastern 96Alaska, and the valley of Mackenzie River have species of black-spotted trout. There are few of these north of Sitka in Alaska, although black-spotted trout are occasionally taken on Kadiak and about Bristol Bay, and none east of the Rocky Mountain region. If we are to follow the usage of the names "salmon" and "trout" which prevails in England, we should say that, in America, it is only these western regions which have any trout at all. Of the number of species (about twenty-five in all) which have been indicated by authors, certainly not more than about 8 to 10 can possibly be regarded as distinct species. The other names are either useless synonyms, or else they have been applied to local varieties which pass by degrees into the ordinary types.

The Trout of Western America.—In the western part of America are found more than a score of forms of trout of the genus Salmo, all closely related and difficult to distinguish. There are representatives in the head-waters of the Rio Grande, Arkansas, South Platte, Missouri, and Colorado rivers; also in the Great Salt Lake basin, throughout the Columbia basin, in all suitable waters from southern California and Chihuahua to Sitka, and even to Bristol Bay, similar forms again appearing in Kamchatka and Japan.

Among the various more or less tangible species that may be recognized, three distinct series appear. These have been termed the cutthroat-trout series (allies of Salmo clarkii), the rainbow-trout series (allies of Salmo irideus), and the steelhead series (allies of Salmo rivularis, a species more usually but wrongly called Salmo gairdneri).

The steelhead, or rivularis series, is found in the coastwise streams of California and in the streams of Oregon and Washington, below the great Shoshone Falls of Snake River, and northward in Alaska along the mainland as far as Skaguay. The steelhead-trout reach a large size (10 to 20 pounds). They spend a large part of their life in the sea. In all the true steelheads the head is relatively very short, its length being contained about five times in the distance from tip of snout to base of caudal fin. The scales in the steelhead are always rather small, about 150 in a linear series, and there is no red under the throat. The spots on the dorsal fin are fewer in the steelhead (4 to 6 rows) than in the other American trout.

97The rainbow forms are chiefly confined to the streams of California and Oregon. In these the scales are large (about 135 in a lengthwise series) and the head is relatively large, forming nearly one-fourth of the length to base of caudal. These enter the sea only when in the small coastwise streams. Usually they have no red under the throat. The cutthroat forms are found from Humboldt Bay northward as far as Sitka, in the coastwise streams of northern California, Oregon, Washington, and Alaska, and all the clear streams on both sides of the Rocky Mountains, and in the Great Basin and the head-waters of the Colorado. The cutthroat-trout have the scales small, about 180, and there is always a bright dash of orange-red on each side concealed beneath the branches of the lower jaw. Along the western slope of the Sierra Nevada there are also forms of trout with the general appearance of rainbow-trout and evidently belonging to that species, but with scales intermediate in number (in McCloud River), var. shasta, or with scales as small as in the typical cutthroat (Kern River), var. gilberti. In these small-scaled forms more or less red appears below the lower jaw, and they are doubtless what they appear to be, really intermediate between clarkii and irideus, although certainly nearest the latter. A similar series of forms occurs in the Columbia basin, the upper Snake being inhabited by clarkii and the lower Snake by clarkii and rivularis, together with a medley of forms apparently intermediate.

It seems probable that the American trout originated in Asia, extended its range to southeast Alaska, thence southward to the Fraser and Columbia, thence to the Yellowstone and the Missouri via Two-Ocean Pass; from the Snake River to the Great Basins of Utah and Nevada; from the Missouri southward to the Platte and the Arkansas, thence from the Platte to the Rio Grande and the Colorado, and then from Oregon southward coastwise and along the Sierras to northern Mexico, thence northward and coastwise, the sea-running forms passing from stream to stream.

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Fig. 61.—Rainbow Trout (male), Salmo irideus shasta Jordan. (Photograph by Cloudsley Rutter.)

Of the American species the rainbow trout of California (Salmo irideus) most nearly approaches the European Salmo fario. It has the scales comparatively large, although rather smaller than in Salmo fario, the usual number in a longitudinal series being about 135. The mouth is smaller than in other American trout; the maxillary, except in old males, rarely extending beyond the eye. The caudal fin is well forked, becoming in very old fishes more nearly truncate. The head is relatively large, about four times in the total length. The size of the head forms the best distinctive character. The color, as in all the other species, is bluish, the sides silvery in the males, with a red lateral band, and reddish and dusky blotches. The head, back, and upper fins are sprinkled with round black spots, which are very variable in number, those on the dorsal usually in about nine rows. In specimens taken in the sea this species, like most other trout in similar conditions, is bright silvery, and sometimes immaculate. This species is especially characteristic of the waters of California. It abounds in every clear brook, from the Mexican line northward to Mount Shasta, or beyond, the species passing in the Columbia region by degrees into the species or form known as Salmo masoni, the Oregon rainbow trout, a small rainbow trout common in the forest streams of Oregon, with smaller mouth and fewer spots on the dorsal. No true rainbow trout have been anywhere obtained to the eastward of the Cascade Range or of the Sierra Nevada, except as artificially planted in the Truckee River. The species varies much in size; specimens from northern California often reach a weight of six pounds, while in the streams above Tia Juana in Lower California the southernmost 99locality from which I have obtained trout, they seldom exceed a length of six inches. Although not usually an anadromous species, the rainbow trout frequently moves about in the rivers, and it often enters the sea, large sea-run specimens being often taken for steelheads. Several attempts have been made to introduce it in Eastern streams, but it appears to seek the sea when it is lost. It is apparently more hardy and less greedy than the American charr, or brook-trout (Salvelinus fontinalis). On the other hand, it is distinctly inferior to the latter in beauty and in gaminess.

Fig. 62.—Rainbow Trout (female), Salmo irideus shasta Jordan. (Photograph by Cloudsley Rutter.)

Three varieties of some importance have been indicated, Salmo irideus stonei, the Nissui trout of the Klamath, with spots on the posterior parts only, Salmo irideus shasta of the upper Sacramento, and the small-scaled Salmo irideus gilberti of the Kings and Kern rivers. In the head-waters of the Kern, in a stream called Volcano Creek or Whitney Creek, the waterfall sometimes called Agua-Bonita shuts off the movements of the trout. Above this fall is a dwarf form with bright golden fins, and the scales scarcely imbricated. This is the "golden trout of Mount Whitney," Salmo irideus agua-bonita. It will possibly be found to change back to the original type if propagated in different waters.

In beauty of color, gracefulness of form and movement, 100sprightliness when in the water, reckless dash with which it springs from the water to meet the descending fly ere it strikes the surface, and the mad and repeated leaps from the water when hooked, the rainbow trout must ever hold a very high rank. "The gamest fish we have ever seen," writes Dr. Evermann, "was a 16-inch rainbow taken on a fly in a small spring branch tributary of Williamson River in southern Oregon. It was in a broad and deep pool of exceedingly clear water. As the angler from behind a clump of willows made the cast the trout bounded from the water and met the fly in the air a foot or more above the surface; missing it, he dropped upon the water, only to turn about and strike viciously a second time at the fly just as it touched the surface; though he again missed the fly, the hook caught him in the lower jaw from the outside, and then began a fight which would delight the heart of any angler. His first effort was to reach the bottom of the pool, then, doubling upon the line, he made three jumps from the water in quick succession, clearing the surface in each instance from one to four feet, and every time doing his utmost to free himself from the hook by shaking his head as vigorously as a dog shakes a rat. Then he would rush wildly about in the large pool, now attempting to go down over the riffle below the pool, now trying the opposite direction, and often striving to hide under one or the other of the banks. It was easy to handle the fish when the dash was made up or down stream or for the opposite side, but when he turned about and made a rush for the protection of the overhanging bank upon which the angler stood it was not easy to keep the line taut. Movements such as these were frequently repeated, and two more leaps were made. But finally he was worn out after as honest a fight as trout ever made."

"The rainbow takes the fly so readily that there is no reason for resorting to grasshoppers, salmon-eggs, or other bait. It is a fish whose gaminess will satisfy the most exacting of expert anglers and whose readiness to take any proper line will please the most impatient of inexperienced amateurs."

The steelhead (Salmo rivularis) is a large trout, reaching twelve to twenty pounds in weight, found abundantly in river estuaries and sometimes in lakes from Lynn Canal to Santa 101Barbara. The spent fish abound in the rivers in spring at the time of the salmon-run. The species is rarely canned, but is valued for shipment in cold storage. Its bones are much more firm than those of the salmon—a trait unfavorable for canning purposes. The flesh when not spent after spawning is excellent. The steelhead does not die after spawning, as all the Pacific salmon do.

Fig. 63.—Steelhead Trout, Salmo rivularis Ayres. Columbia River.

It is thought by some anglers that the young fish hatched in the brooks from eggs of the steelhead remain in mountain streams from six to thirty-six months, going down to the sea with the high waters of spring, after which they return to spawn as typical steelhead trout. I now regard this view as unfounded. In my experience the rainbow and the steelhead are always distinguishable: the steelhead abounds where the rainbow trout is unknown; the scales in the steelhead are always smaller (about 155) than in typical rainbow trout; finally, the small size of the head in the steelhead is always distinctive.

The Kamloops trout, described by the writer from the upper Columbia, seems to be a typical steelhead as found well up the rivers away from the sea. Derived from the steelhead, but apparently quite distinct from it, are three very noble trout, all confined so far as yet known to Lake Crescent in northwestern Washington. These are the crescent trout, Salmo crescentis, the Beardslee trout, Salmo beardsleei, and the long-headed trout, Salmo bathæcetor. The first two, discovered by Admiral L. A. Beardslee, are trout of peculiar attractiveness and excellence. The third is a deep-water form, never rising to the surface, and caught only on set lines. Its origin is still uncertain, and it may be derived from some type other than the steelhead.

102Cutthroat or Red-throated Trout.—This species has much smaller scales than the rainbow trout or steelhead, the usual number in a longitudinal series being 160 to 170. Its head is longer (about four times in length to base of caudal). Its mouth is proportionately larger, and there is always a narrow band of small teeth on the hyoid bone at the base of the tongue. These teeth are always wanting in Salmo irideus and rivularis in which species the rim of the tongue only has teeth. The color in Salmo clarkii is, as in other species, exceedingly variable. In life there is always a deep-red blotch on the throat, between the branches of the lower jaw and the membrane connecting them. This is not found in other species, or is reduced to a narrow strip or pinkish shade. It seems to be constant in all varieties of Salmo clarkii, at all ages, thus furnishing a good distinctive character. It is the sign manual of the Sioux Indians, and the anglers have already accepted from this mark the name of cutthroat-trout. The cutthroat-trout of some species is found in every suitable river and lake in the great basin of Utah, in the streams of Colorado, Wyoming, and Montana, on both sides of the Rocky Mountains. It is also found throughout Oregon, Washington, Idaho, British Columbia, the coastwise islands of southeastern Alaska (Baranof, etc.), to Kadiak and Bristol Bay, probably no stream or lake suitable for trout-life being without it. In California the species seems to be comparatively rare, and its range rarely extending south of Cape Mendocino. Large sea-run individuals analogous to the steelheads are sometimes found in the mouth of the Sacramento. In Washington and Alaska this species regularly enters the sea. In Puget Sound it is a common fish. These sea-run individuals are more silvery and less spotted than those found in the mountain streams and lakes. The size of Salmo clarkii is subject to much variation. Ordinarily four to six pounds is a large size; but in certain favored waters, as Lake Tahoe, and the fjords of southeastern Alaska, specimens from twenty to thirty pounds are occasionally taken.

Those species or individuals dwelling in lakes of considerable size, where the water is of such temperature and depth as insures an ample food-supply, will reach a large size, while those in a restricted environment, where both the water and food are 103limited, will be small directly in proportion to these environing restrictions. The trout of the Klamath Lakes, for example, reach a weight of at least 17 pounds, while in Fish Lake in Idaho mature trout do not exceed 8 to 9¼ inches in total length or one-fourth pound in weight. In small creeks in the Sawtooth Mountains and elsewhere they reach maturity at a length of 5 or 6 inches, and are often spoken of as brook-trout and with the impression that they are a species different from the larger ones found in the lakes and larger streams. But as all sorts and gradations between these extreme forms may be found in the intervening and connecting waters, the differences are not even of sub-specific significance.

Fig. 64.—Head of adult Trout-worm, Dibothrium cordiceps Leidy, a parasite of Salmo clarkii. From intestine of white pelican, Yellowstone Lake. (After Linton.)

Fig. 65.—Median segments of Dibothrium cordiceps.

Dr. Evermann observes: "The various forms of cutthroat-trout vary greatly in game qualities; even the same subspecies in different waters, in different parts of its habitat, or at different seasons, will vary greatly in this regard. In general, however, it is perhaps a fair statement to say that the cutthroat-trout are regarded by anglers as being inferior in gaminess to the Eastern brook-trout. But while this is true, it must not by any means be inferred that it is without game qualities, for it is really a fish which possesses those qualities in a very high degree. Its vigor and voraciousness are determined largely, of course, by the character of the stream or lake in which it lives. The individuals which dwell in cold streams about cascades and seething rapids will show marvelous strength and will make a fight which is rarely equaled by its Eastern cousin; while in warmer and larger streams and lakes they may be very sluggish and show but little fight. Yet this is by no means always true. In the Klamath Lakes, where the trout grow very large and 104where they are often very logy, one is occasionally hooked which tries to the utmost the skill of the angler to prevent his tackle from being smashed and at the same time save the fish."

Of the various forms derived from Salmo clarkii some mere varieties, some distinct species, the following are among the most marked:

Salmo henshawi, the trout of Lake Tahoe and its tributaries and outlet, Truckee River, found in fact also in the Humboldt and the Carson and throughout the basin of the former glacial lake called Lake Lahontan. This is a distinct species from Salmo clarkii and must be regarded as the finest of all the cutthroat-trout. It is readily known by its spotted belly, the black spots being evenly scattered over the whole surface of the body, above and below. This is an excellent game-fish, and from Lake Tahoe and Pyramid Lake it is brought in large numbers to the markets of San Francisco. In the depths of Lake Tahoe, which is the finest mountain lake of the Sierra Nevada, occurs a very large variety which spawns in the lake, Salmo henshawi tahoensis. This reaches a weight of twenty-eight pounds.

Fig. 66.—Tahoe Trout, Salmo henshawi Gill & Jordan. Lake Tahoe, California.

In the Great Basin of Utah is found a fine trout, very close to the ordinary cutthroat of the Columbia, from which it is derived. This is known as Salmo clarkii virginalis. In Utah Lake it reaches a large size.

In Waha Lake in Washington, a lake without outlet, is found a small trout with peculiar markings called Salmo clarkii bouvieri.

In the head-waters of the Platte and Arkansas rivers is the small green-back trout, green or brown, with red throat-patch 105and large black spots. This is Salmo clarkii stomias, and it is especially fine in St. Vrain's River and the streams of Estes Park. In Twin Lakes, a pair of glacial lakes tributary of the Arkansas near Leadville, is found Salmo clarkii macdonaldi, the yellow-finned trout, a large and very handsome species living in deep water, and with the fins golden yellow. This approaches the Colorado trout, Salmo clarkii pleuriticus, and it may be derived from the latter, although it occurs in the same waters as the very different green-back trout, or Salmo clarkii stomias.

Fig. 67.—Green-back Trout, Salmo stomias Cope. Arkansas River, Leadville, Colo.

Fig. 68.—Yellow-fin Trout of Twin Lakes, Salmo macdonaldi Jordan & Evermann. Twin Lakes, Colo.

Two fine trout derived from Salmo clarkii have been lately discovered by Dr. Daniel G. Elliot in Lake Southerland, a mountain lake near Lake Crescent, but not connected with it, the two separated from the sea by high waterfalls. These have been described by Dr. Seth E. Meek as Salmo jordani, the "spotted trout" of Lake Southerland, and Salmo declivifrons, the "salmon-trout." These seem to be distinct forms or subspecies produced through isolation.

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Fig. 69.—Rio Grande Trout, Salmo clarkii spilurus Cope. Del Norte, Colo.

Fig. 70.—Colorado River Trout, Salmo clarkii pleuriticus Cope. Trapper's Lake, Colo.

The Rio Grande trout (Salmo clarkii spilurus) is a large and profusely spotted trout, found in the head-waters of the Rio Grande, the mountain streams of the Great Basin of Utah, and as far south as the northern part of Chihuahua. Its scales are still smaller than those of the ordinary cutthroat-trout, and the black spots are chiefly confined to the tail. Closely related to it is the trout of the Colorado Basin, Salmo clarkii pleuriticus, a large and handsome trout with very small scales, much sought by anglers in western Colorado, and abounding in all suitable streams throughout the Colorado Basin.

Hucho, the Huchen.—The genus Hucho has been framed for the Huchen or Rothfisch (Hucho hucho) of the Danube, a very large trout, differing from the genus Salmo in having no teeth on the shaft of the vomer, and from the Salvelini at least in form and coloration. The huchen is a long and slender, somewhat pike-like fish, with depressed snout and strong teeth. 107The color is silvery, sprinkled with small black dots. It reaches a size little inferior to that of the salmon, and it is said to be an excellent food-fish. In northern Japan is a similar species, Hucho blackistoni, locally known as Ito, a large and handsome trout with very slender body, reaching a length of 2½ feet. It is well worthy of introduction into American and European waters.

Fig. 71.—Ito, Hucho blackistoni (Hilgendorf). Hokkaido, Japan.

Salvelinus, the Charr.—The genus Salvelinus comprises the finest of the Salmonidæ, from the point of view of the angler or the artist. In England the species are known as charr or char, in contradistinction to the black-spotted species of Salmo, which are called trout. The former name has unfortunately been lost in America, where the name "trout" is given indiscriminately to both groups, and, still worse, to numerous other fishes (Micropterus, Hexagrammos, Cynoscion, Agonostomus) wholly unlike the Salmonidæ in all respects. It is sometimes said that "the American brook-trout is no trout, nothing but a charr," almost as though "charr" were a word of reproach. Nothing higher, however, can be said of a salmonoid than that it is a "charr." The technical character of the genus Salvelinus lies in the form of its vomer. This is deeper than in Salmo; and when the flesh is removed the bone is found to be somewhat boat-shaped above, and with the shaft depressed and out of the line of the head of the vomer. Only the head or chevron is armed with teeth, and the shaft is covered by skin.

In color all the charrs differ from the salmon and trout. The body in all is covered with round spots which are paler than the ground color, and crimson or gray. The lower fins are 108usually edged with bright colors. The sexual differences are not great. The scales, in general, are smaller than in other Salmonidæ, and they are imbedded in the skin to such a degree as to escape the notice of casual observers and even of most anglers.

The charrs inhabit, in general, only the clearest and coldest of mountain streams and lakes, or bays of similar temperature. They are not migratory, or only to a limited extent. In northern regions they descend to the sea, where they grow much more rapidly and assume a nearly uniform silvery-gray color. The different species are found in all suitable waters throughout the northern parts of both continents, except in the Rocky Mountains and Great Basin, where only the black-spotted trout occur. The number of species of charr is very uncertain, as, both in America and Europe, trivial variations and individual peculiarities have been raised to the rank of species. More types, however, seem to be represented in America than in Europe.

Fig. 72.—Rangeley Trout, Salvelinus oquassa (Girard). Lake Oquassa, Maine.

The only really well-authenticated species of charr in European waters is the red charr, sälbling, or ombre chevalier (Salvelinus alpinus). This species is found in cold, clear streams in Switzerland, Germany, and throughout Scandinavia and the British Islands. Compared with the American charr or brook-trout, it is a slenderer fish, with smaller mouth, longer fins, and smaller red spots, which are confined to the sides of the 109body. It is a "gregarious and deep-swimming fish, shy of taking the bait and feeding largely at night-time. It appears to require very pure and mostly deep water for its residence." It is less tenacious of life than the trout. It reaches a weight of from one to five pounds, probably rarely exceeding the latter in size. The various charr described from Siberia are far too little known to be enumerated here.

Of the American charr the one most resembling the European species is the Rangeley Lake trout (Salvelinus oquassa). The exquisite little fish is known in the United States only from the Rangeley chain of lakes in western Maine. This is very close to the Greenland charr, Salvelinus stagnalis, a beautiful species of the far north. The Rangeley trout is much slenderer than the common brook-trout, with much smaller head and smaller mouth. In life it is dark blue above, and the deep-red spots are confined to the sides of the body. The species rarely exceeds the length of a foot in the Rangeley Lakes, but in some other waters it reaches a much larger size. So far as is known it keeps itself in the depths of the lake until its spawning season approaches, in October, when it ascends the stream to spawn.

Fig. 73.—Sunapee Trout, Salvelinus aureolus Bean. Sunapee Lake, N. H.

Still other species of this type are the Sunapee trout, Salvelinus aureolus, a beautiful charr almost identical with the European species, found in numerous ponds and lakes of eastern New Hampshire and neighboring parts of Maine. Mr. Garman regards this trout as the offspring of an importation of the ombre chevalier and not as a native species, and in this view he may be correct. Salvelinus alipes of the far north may be the same species. Another remarkable form is the Lac de Marbre trout of Canada, Salvelinus marstoni of Garman.

110In Arctic regions another species, called Salvelinus naresi, is very close to Salvelinus oquassa and may be the same.

Another beautiful little charr, allied to Salvelinus stagnalis, is the Floeberg charr (Salvelinus arcturus). This species has been brought from Victoria Lake and Floeberg Beach, in the extreme northern part of Arctic America, the northernmost point whence any salmonoid has been obtained.

Fig. 74.—Speckled Trout (male), Salvelinus fontinalis (Mitchill). New York.

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Fig. 75.—Brook Trout, Salvelinus fontinalis (Mitchill), natural size. (From life by Dr. R. W. Shufeldt.)

112The American charr, or, as it is usually called, the brook-trout (Salvelinus fontinalis), although one of the most beautiful of fishes, is perhaps the least graceful of all the genuine charrs. It is technically distinguished by the somewhat heavy head and large mouth, the maxillary bone reaching more or less beyond the eye. There are no teeth on the hyoid bone, traces at least of such teeth being found in nearly all other species. Its color is somewhat different from that of the others, the red spots being large and the black more or less mottled and barred with darker olive. The dorsal and caudal fins are likewise barred or mottled, while in the other species they are generally uniform in color. The brook-trout is found only in streams east of the Mississippi and Saskatchewan. It occurs in all suitable streams of the Alleghany region and the Great Lake system, from the Chattahoochee River in northern Georgia northward at least to Labrador and Hudson Bay, the northern limits of its range being as yet not well ascertained. It varies greatly in size, according to its surroundings, those found in lakes being larger than those resident in small brooks. Those found farthest south, in the head-waters of the Chattahoochee, Savannah, Catawba, and French Broad, rarely pass the dimensions of fingerlings. The largest specimens are recorded from the sea along the Canadian coast. These frequently reach a weight of ten pounds; and from their marine and migratory habits, they have been regarded as forming a distinct variety (Salvelinus fontinalis immaculatus), but this form is merely a sea-run brook-trout. The largest fresh-water specimens rarely exceed seven pounds in weight. Some unusually large brook-trout have been taken in the Rangeley Lakes, the largest known to me having a reputed weight of eleven pounds. The brook-trout is the favorite game-fish of American waters, preëminent in wariness, in beauty, and in delicacy of flesh. It inhabits all clear and cold waters within its range, the large lakes and the smallest ponds, the tiniest brooks and the largest rivers; and when it can do so without soiling its aristocratic gills on the way, it descends to the sea and grows large and fat on the animals of the ocean. Although a bold biter it is a wary fish, and it often requires much skill to capture it. It can be caught, too, with artificial or natural flies, minnows, crickets, worms, grasshoppers, grubs, the spawn of other fish, or even the eyes or cut pieces of other trout. It spawns in the fall, from September to late in November. It begins to reproduce at the age of two years, then having a length of about six inches. In spring-time the trout delight in rapids and swiftly running water; and in the hot months of midsummer they resort to deep, cool, and shaded pools. Later, at the approach of the spawning season, they gather around the mouths of cool, gravelly brooks, whither they resort to make their beds.^[10]

The trout are rapidly disappearing from our streams through the agency of the manufacturer and the summer boarder. In the words of an excellent angler, the late Myron W. Reed of Denver: "This is the last generation of trout-fishers. The children will not be able to find any. Already there are well-trodden paths by every stream in Maine, in New York, and in Michigan. I know of but one river in North America by the side of which you will find no paper collar or other evidence of civilization. It is the Nameless River. Not that trout will 113cease to be. They will be hatched by machinery and raised in ponds, and fattened on chopped liver, and grow flabby and lose their spots. The trout of the restaurant will not cease to be. He is no more like the trout of the wild river than the fat and songless reedbird is like the bobolink. Gross feeding and easy pond-life enervate and deprave him. The trout that the children will know only by legend is the gold-sprinkled, living arrow of the white water; able to zigzag up the cataract; able to loiter in the rapids; whose dainty meat is the glancing butterfly."

The brook-trout adapts itself readily to cultivation in artificial ponds. It has been successfully transported to Europe, and it is already abundant in certain streams in England, in California, and elsewhere.

In Dublin Pond, New Hampshire, is a gray variety without red spots, called Salvelinus agassizi.

Fig. 76.—Malma Trout, or "Dolly Varden," Salvelinus malma (Walbaum). Cook Inlet, Alaska.

The "Dolly Varden" trout, or malma (Salvelinus malma), is very similar to the brook-trout, closely resembling it in size, form, color, and habits. It is found always to the westward of the Rocky Mountains, in the streams of northern California, Oregon, Washington, and British Columbia, Alaska, and Kamchatka, as far as the Kurile Islands. It abounds in the sea in the northward, and specimens of ten to twelve pounds weight are not uncommon in Puget Sound and especially in Alaska. The Dolly Varden trout is, in general, slenderer and less compressed than the Eastern brook-trout. The red spots are found on the back of the fish as well as on the sides, and the back and upper fins are without the blackish marblings and blotches seen in 114Salvelinus fontinalis. In value as food, in beauty, and in gaminess Salvelinus malma is very similar to its Eastern cousin.

Fig. 77.—The Dolly Varden Trout, Salvelinus malma (Walbaum). Lake Pend d'Oreille, Idaho. (After Evermann.)

In Alaska the Dolly Varden, locally known as salmon-trout, is very destructive to the eggs of the salmon, and countless numbers are taken in the salmon-nets of Alaska and thrown away as useless by the canners. In every coastwise stream of Alaska the water fairly "boils" with these trout. They are, however, not found in the Yukon. In northern Japan occurs Salvelinus pluvius, the iwana, a species very similar to the Dolly Varden, but not so large or so brightly colored. In the Kurile region and Kamchatka is another large charr, Salvelinus kundscha, with the spots large and cream-color instead of crimson.

Fig. 78.—Great Lake Trout, Cristivomer namaycush (Walbaum). Lake Michigan.

Cristivomer, the Great Lake Trout.—Allied to the true charrs, but now placed by us in a different genus, Cristivomer, is the Great Lake trout, otherwise known as Mackinaw trout, longe, or togue (Cristivomer namaycush). Technically this fish differs from the true charrs in having on its vomer a raised crest behind 115the chevron and free from the shaft. This crest is armed with strong teeth. There are also large hooked teeth on the hyoid bone, and the teeth generally are proportionately stronger than in most of the other species. The Great Lake trout is grayish in color, light or dark according to its surroundings; and the body is covered with round paler spots, which are gray instead of red. The dorsal and caudal fins are marked with darker reticulations, somewhat as in the brook-trout. This noble species is found in all the larger lakes from New England and New York to Wisconsin, Montana, the Mackenzie River, and in all the lakes tributary to the Yukon in Alaska. We have taken examples from Lake Bennett, Lake Tagish, Summit Lake (White Pass), and have seen specimens from Lake La Hache in British Columbia. It reaches a much larger size than any Salvelinus, specimens of from fifteen to twenty pounds weight being not uncommon, while it occasionally attains a weight of fifty to eighty pounds. As a food-fish it ranks high, although it may be regarded as somewhat inferior to the brook-trout or the whitefish. Compared with other salmonoids, the Great Lake trout is a sluggish, heavy, and ravenous fish. It has been known to eat raw potato, liver, and corn-cobs,—refuse thrown from passing steamers. According to Herbert, "a coarse, heavy, stiff rod, and a powerful oiled hempen or flaxen line, on a winch, with a heavy sinker; a cod-hook, baited with any kind of flesh, fish, or fowl,—is the most successful, if not the most orthodox or scientific, mode of capturing him. His great size and immense strength alone give him value as a fish of game; but when hooked he pulls strongly and fights hard, though he is a boring, deep fighter, and seldom if ever leaps out of the water, like the true salmon or brook-trout."

In the depths of Lake Superior is a variety of the Great Lake trout known as the Siscowet (Cristivomer namaycush siskawitz), remarkable for its extraordinary fatness of flesh. The cause of this difference lies probably in some peculiarity of food as yet unascertained.

The Ayu, or Sweetfish.—The ayu, or sweetfish, of Japan, Plecoglossus altivelis, resembles a small trout in form, habits, and scaling. Its teeth are, however, totally different, being arranged on serrated plates on the sides of the jaws, and the tongue marked with similar folds. The ayu abounds in all 116clear streams of Japan and Formosa. It runs up from the sea like a salmon. It reaches the length of about a foot. The flesh is very fine and delicate, scarcely surpassed by that of any other fish whatsoever. It should be introduced into clear short streams throughout the temperate zones.

Fig. 79.—Ayu, or Japanese Samlet, Plecoglossus altivelis Schlegel. Tamagawa, Tokyo, Japan.

In the river at Gifu in Japan and in some other streams the ayu is fished for on a large scale by means of tamed cormorants. This is usually done from boats in the night by the light of torches.

Cormorant-fishing.—The following account of cormorant-fishing is taken, by the kind permission of Mr. Caspar W. Whitney, from an article contributed by the writer to Outing, April, 1902:

Tamagawa means Jewel River, and no water could be clearer. It rises somewhere up in the delectable mountains to the eastward of Musashi, among the mysterious pines and green-brown fir-trees, and it flows across the plains bordered by rice-fields and mulberry orchards to the misty bay of Tokyo. It is, therefore, a river of Japan, and along its shores are quaint old temples, each guarding its section of primitive forest, picturesque bridges, huddling villages, and torii, or gates through which the gods may pass.

The stream itself is none too large—a boy may wade it—but it runs on a wide bed, which it will need in flood-time, when the snow melts in the mountains. And this broad flood-bed is 117filled with gravel, with straggling willows, showy day-lilies, orange amaryllis, and the little sky-blue spider-flower, which the Japanese call chocho, or butterfly-weed.

In the Tamagawa are many fishes: shining minnows in the white ripples, dark catfishes in the pools and eddies, and little sculpins and gobies lurking under the stones. Trout dart through its upper waters, and at times salmon run up from the sea.

But the one fish of all its fishes is the ayu. This is a sort of dwarf salmon, running in the spring and spawning in the rivers just as a salmon does. But it is smaller than any salmon, not larger than a smelt, and its flesh is white and tender, and so very delicate in its taste and odor that one who tastes it crisply fried or broiled feels that he has never tasted real fish before. In all its anatomy the ayu is a salmon, a dwarf of its kind, one which our ancestors in England would have called a "samlet." Its scientific name is Plecoglossus altivelis. Plecoglossus means plaited tongue, and altivelis, having a high sail; for the skin of the tongue is plaited or folded in a curious way, and the dorsal fin is higher than that of the salmon, and one poetically inclined might, if he likes, call it a sail. The teeth of the ayu are very peculiar, for they constitute a series of saw-edged folds or plaits along the sides of the jaws, quite different from those of any other fish whatsoever.

In size the ayu is not more than a foot to fifteen inches long. It is like a trout in build, and its scales are just as small. It is light yellowish or olive in color, growing silvery below. Behind its gills is a bar of bright shining yellow, and its adipose fin is edged with scarlet. The fins are yellow, and the dorsal fin shaded with black, while the anal fin is dashed with pale red.

So much for the river and the ayu. It is time for us to go afishing. It is easy enough to find the place, for it is not more than ten miles out of Tokyo, on a fine old farm just by the ancient Temple of Tachikawa, with its famous inscribed stone, given by the emperor of China.

At the farmhouse, commodious and hospitable, likewise clean and charming after the fashion of Japan, we send for the boy who brings our fishing-tackle.

118They come waddling into the yard, the three birds with which we are to do our fishing. Black cormorants they are, each with a white spot behind its eye, and a hoarse voice, come of standing in the water, with which it says y-eugh whenever a stranger makes a friendly overture. The cormorants answer to the name of Ou, which in Japanese is something like the only word the cormorants can say. The boy puts them in a box together and we set off across the drifted gravel to the Tamagawa. Arrived at the stream, the boy takes the three cormorants out of the box and adjusts their fishing-harness. This consists of a tight ring about the bottom of the neck, of a loop under each wing, and a directing line.

Two other boys take a low net. They drag it down the stream, driving the little fishes—ayu, zakko, haë, and all the rest—before it. The boy with the cormorants goes in advance. The three birds are eager as pointer dogs, and apparently full of perfect enjoyment. To the right and left they plunge with lightning strokes, each dip bringing up a shining fish. When the bird's neck is full of fishes down to the level of the shoulders, the boy draws him in, grabs him by the leg, and shakes him unceremoniously over a basket until all the fishes have flopped out.

The cormorants watch the sorting of the fish with eager eyes and much repeating of y-eugh, the only word they know. The ayu are not for them, and some of the kajikas and hazés were prizes of science. But zakko (the dace) and haë (the minnow) were made for the cormorant. The boy picks out the chubs and minnows and throws them to one bird and then another. Each catches his share on the fly, swallows it at one gulp, for the ring is off his neck by this time, and then says y-eugh, which means that he likes the fun, and when we are ready will be glad to try again. And no doubt they have tried it many times since, for there are plenty of fishes in the Jewel River, zakko and haë as well as ayu.

Fossil Salmonidæ.—Fossil salmonidæ are rare and known chiefly from detached scales, the bones in this family being very brittle and easily destroyed. Nothing is added to our knowledge of the origin of these fishes from such fossils.

A large fossil trout or salmon, called Rhabdofario lacustris, 119has been brought from the Pliocene at Catherine's Creek, Idaho. It is known from the skull only. Thaumaturus luxatus, from the Miocene of Bohemia, shows the print of the adipose fin. As already stated (p. 62), fragments of the hooked jaws of salmon, from pleistocene deposits in Idaho, are in the museum of the University of California.

The Grayling, or Thymallidæ.—The small family of Thymallidæ, or grayling, is composed of finely organized fishes allied to the trout, but differing in having the frontal bones meeting on the middle line of the skull, thus excluding the frontals from contact with the supraoccipital. The anterior half of the very high dorsal is made up of unbranched simple rays. There is but one genus, Thymallus, comprising very noble game-fishes characteristic of subarctic streams.

Fig. 80.—Alaska Grayling, Thymallus signifer Richardson. Nulato, Alaska.

The grayling, Thymallus, of Europe, is termed by Saint Ambrose "the flower of fishes." The teeth on the tongue, found in all the trout and salmon, are obsolete in the grayling. The chief distinctive peculiarity of the genus Thymallus is the great development of the dorsal fin, which has more rays (20 to 24) than are found in any of the Salmonidæ, and the fin is also higher. All the species are gaily colored, the dorsal fin especially being marked with purplish or greenish bands 121and bright rose-colored spots; while the body is mostly purplish gray, often with spots of black. Most of the species rarely exceed a foot in length, but northward they grow larger. Grayling weighing five pounds have been taken in England; and according to Dr. Day they are said in Lapland to reach a weight of eight or nine pounds. The grayling in all countries frequent clear, cold brooks, and rarely, if ever, enter the sea, or even the larger lakes. They congregate in small shoals in the streams, and prefer those which have a succession of pools and shallows, with a sandy or gravelly rather than rocky bottom. The grayling spawns on the shallows in April or May (in England). It is non-migratory in its habits, depositing its ova in the neighborhood of its usual haunts. The ova are far more delicate and easily killed than those of the trout or charr. The grayling and the trout often inhabit the same waters, but not altogether in harmony. It is said that the grayling devours the eggs of the trout. It is certain that the trout feed on the young grayling. As a food-fish, the grayling of course ranks high; and it is beloved by the sportsman. They are considered gamy fishes, although less strong than the brook-trout, and perhaps less wary. The five or six known species of grayling are very closely related, and are doubtless comparatively recent offshoots from a common stock, which has now spread itself widely through the northern regions.

The common grayling of Europe (Thymallus thymallus) is found throughout northern Europe, and as far south as the mountains of Hungary and northern Italy. The name Thymallus was given by the ancients, because the fish, when fresh, was said to have the odor of water-thyme. Grayling belonging to this or other species are found in the waters of Russia and Siberia.

The American grayling (Thymallus signifer) is widely distributed in British America and Alaska. In the Yukon it is very abundant, rising readily to the fly. In several streams in northern Michigan, Au Sable River, and Jordan River in the southern peninsula, and Otter Creek near Keweenaw in the northern peninsula, occurs a dwarfish variety or species with shorter and lower dorsal fins, known to anglers as the Michigan grayling (Thymallus tricolor). This form has a longer head, rather smaller scales, and the dorsal fin rather lower than in 122the northern form (signifer); but the constancy of these characters in specimens from intermediate localities is yet to be proved. Another very similar form, called Thymallus montanus, occurs in the Gallatin, Madison, and other rivers of Western Montana tributary to the Missouri. It is locally still abundant and one of the finest of game-fishes. It is probable that the grayling once had a wider range to the southward than now, and that so far as the waters of the United States are concerned it is tending toward extinction. This tendency is, of course, being accelerated in Michigan by lumbermen and anglers. The colonies of grayling in Michigan and Montana are probably remains of a post-glacial fauna.

Fig. 81.—Michigan Grayling, Thymallus tricolor Cope. Au Sable River, Mich.

The Argentinidæ.—The family of Argentinidæ, or smelt, is very closely related to the Salmonidæ, representing a dwarf series of similar type. The chief essential difference lies in the form of the stomach, which is a blind sac, the two openings near together, and about the second or pyloric opening there are few if any pyloric cæca. In all the Salmonidæ the stomach has the form of a siphon, and about the pylorus there are very many pyloric cæca. The smelt have the adipose fin and the general structure of the salmon. All the species are small in size, and most of them are strictly marine, though some of them ascend the rivers to spawn, just as salmon do, but not going very far. A few kinds become landlocked in ponds. Most of the species are confined to the north temperate zone, and a few sink into the deep seas. All that are sufficiently abundant furnish excellent food, the flesh being extremely delicate and often charged with a fragrant oil easy of digestion.

123

Fig. 82.—Smelt, Osmerus mordux (Mitchill). Wood's Hole, Mass.

The best-known genus, Osmerus, includes the smelt, or spirling (éperlan), of Europe, and its relatives, all excellent food-fishes, although quickly spoiling in warm weather. Osmerus eperlanus is the European species; Osmerus mordax of our eastern coast is very much like it, as is also the rainbow-smelt, Osmerus dentex of Japan and Alaska. A larger smelt, Osmerus albatrossis, occurs on the coast of Alaska, and a small and feeble one, Osmerus thaleichthys, mixed with other small or delicate fishes, is the whitebait of the San Francisco restaurants. The whitebait of the London epicure is made up of the young of herrings and sprats of different species. The still more delicate whitebait of the Hong Kong hotels is the icefish, Salanx chinensis. Retropinna retropinna, so called from the backward insertion of its dorsal, is the excellent smelt of the rivers of New Zealand. All the other species belong to northern waters. Mesopus, the surf-smelt, has a smaller mouth than Osmerus and inhabits the North Pacific. The California species, Mesopus pretiosus, of Neah Bay has, according to James G. Swan, "the belly covered with a coating of yellow fat which imparts an oily appearance to the water where the fish has been cleansed or washed and makes them the very perfection of pan-fish." This species spawns in late summer along the surf-line. According to Mr. Swan the water seems to be filled with them. "They come in with the flood-tide, and when a wave breaks upon the beach they crowd up into the very foam, and as the surf recedes many will be seen flapping on the sand and shingle, but invariably returning with the undertow to deeper water." The Quilliute Indians of Washington believe that "the first 124surf-smelts that appear must not be sold or given away to be taken to another place, nor must they be cut transversely, but split open with a mussel-shell."

The surf-smelt is marine, as is also a similar species, Mesopus japonicus, in Japan. Mesopus olidus, the pond-smelt of Alaska, Kamchatka, and Northern Japan, spawns in fresh-water ponds.

Fig. 83.—Eulachon, or Ulchen. Thaleichthys pretiosus Girard. Columbia River. Family Argentinidæ.

Still more excellent as a food-fish than even these exquisite species is the famous eulachon, or candle-fish (Thaleichthys pacificus). The Chinook name, usually written eulachon, is perhaps more accurately represented as ulchen. This little fish has the form of a smelt and reaches the length of nearly a foot. In the spring it ascends in enormous numbers all the rivers north of the Columbia, as far as Skaguay, for a short distance for the purpose of spawning. These runs take place usually in advance of the salmon-runs. Various predatory fishes and sea-birds persecute the eulachon during its runs, and even the stomachs of the sturgeons are often found full of the little fishes, which they have taken in by their sucker-like mouths. At the time of the runs the eulachon are extremely fat, so much so that it is said that when dried and a wick drawn through the body they may be used as candles. On Nass River, in British Columbia, a stream in which their run is greatest, there is a factory for the manufacture of eulachon-oil from them. This delicate oil is proposed as a substitute for cod-liver oil in medicine. Whatever may be its merits in this regard, it has the disadvantage in respect to salability of being semi-solid or lard-like at ordinary temperatures, requiring melting to make it flow as oil. The eulachon is a favorite pan-fish in British Columbia. The writer has had considerable experience with it, broiled and fried, in its native region, and has no hesitation in declaring it to be the best-flavored food-fish in American waters. It is fat, tender, juicy, and richly flavored, with comparatively few troublesome bones. It does not, however, bear transportation well. The Indians in Alaska bury the eulachon in the ground in great masses. After the fish are well decayed they are taken out and the oil pressed from them. The odor of the fish and the oil is then very offensive, less so, however, than that of some forms of cheese eaten by civilized people.

125

Fig. 84.—Page of William Clark's handwriting with sketch of the Eulachon (Thaleichthys pacificus), the first notice of the species. Columbia River, 1805. (Expedition of Lewis & Clark.) (Reproduced from the original in the possession of his granddaughter Mrs. Julia Clark Voorhis, through the courtesy of Messrs. Dodd, Mead & Company, publishers of the "Original Journals of the Lewis and Clark Expedition.")

126The capelin (Mallotus villosus) closely resembles the eulachon, differing mainly in its broader pectorals and in the peculiar scales of the males. In the male fish a band of scales above the lateral line and along each side of the belly become elongate, closely imbricated, with the free points projecting, giving the body a villous appearance. It is very abundant on the coasts of Arctic America, both in the Atlantic and the Pacific, and is an important source of food for the natives of those regions.

Fig. 85.—Capelin, Mallotus villosus L. Crosswater Bay.

This species spawns in the surf, and the writer has seen them in August cast on the shores of the Alaskan islands (as at Metlakahtla in 1897), living and dead, in numbers which seem incredible. The males are then distorted, and it seems likely that all of them perish after spawning. The young are abundant in all the northern fiords. Even more inordinate numbers are reported from the shores of Greenland.

The capelin seems to be inferior to the eulachon as a food-fish, but to the natives of arctic regions in both hemispheres it is a very important article of food. Fossil capelin are found 127in abundance in recent shales in Greenland enveloped in nodules of clay. In the open waters about the Aleutian Islands a small smelt, Therobromus callorhini, occurs in very great abundance and forms the chief part of the summer food of the fur-seal. Strangely enough, no complete specimen of this fish has yet been seen by man, although thousands of fragments have been taken from seals' stomachs. From these fragments Mr. Frederick A. Lucas has reconstructed the fish, which must be an ally of the surf-smelt, probably spawning in the open ocean of the north.

The silvery species called Argentina live in deeper water and have no commercial importance. Argentina silus, with prickly scales, occurs in the North Sea. Several fossils have been doubtfully referred to Osmerus.

The Microstomidæ.—The small family of Microstomidæ consists of a few degraded smelt, slender in form, with feeble mouth and but three or four branchiostegals, rarely taken in the deep seas. Nansenia grœnlandica was found by Reinhardt off the coast of Greenland, and six or eight other species of Microstoma and Bathylagus have been brought in by the deep-sea explorations.

The Salangidæ, or Icefishes.—Still more feeble and insignificant are the species of Salangidæ, icefishes, or Chinese whitebait, which may be described as Salmonidæ reduced to the lowest terms. The body is long and slender, perfectly translucent, almost naked, and with the skeleton scarcely ossified. The fins are like those of the salmon, the head is depressed, the jaws long and broad, somewhat like the bill of a duck, and within there are a few disproportionately strong canine teeth, those of the lower jaw somewhat piercing the upper. The alimentary canal is straight for its whole length, without pyloric cæca. These little fishes, two to five inches long, live in the sea in enormous numbers and ascend the rivers of eastern Asia for the purpose of spawning. It is thought by some that they are annual fishes, all dying in the fall after reproduction, the species living through the winter only within its eggs. But this is only suspected, not proved, and the species will repay the careful study which some of the excellent naturalists of Japan are sure before long to give to it. The species of Salanx are known as whitebait, in Japan as Shiro-uwo, which means exactly the 128same thing. They are also sometimes called icefish (Hingio), which, being used for no other fish, may be adopted as a group name for Salanx.

The species are Salanx chinensis from Canton, Salanx hyalo cranius from Korea and northern China, Salanx microdon from northern Japan, and Salanx ariakensis from the southern island of Kiusiu. The Japanese fishes are species still smaller and feebler than their relatives from the mainland.

The Haplochitonidæ.—The Haplochitonidæ are trout-like fishes of the south temperate zone, differing from the Salmonidæ mainly in the extension of the premaxillary until, as in the perch-like fishes, it forms the outer border of the upper jaw. The adipose fin is present as in all the salmon and smelt. Haplochiton of Tierra del Fuego and the Falkland Islands is naked, while in Prototroctes of Australia and New Zealand the body, as in all salmon, trout, and smelt, is covered with scales. Prototroctes maræna is the yarra herring of Australia. The closely related family of Galaxiidæ, also Australian, but lacking the adipose fin, is mentioned in a later chapter.

Fig. 86.—Icefish, Salanx hyalocranius Abbott. Family Salangidæ. Tientsin, China.

Stomiatidæ.—The Stomiatidæ, with elongate bodies, have the mouth enormous, with fang-like teeth, usually barbed. Of the several species Stomias ferox is best known. According to Dr. Boulenger, these fishes are true Isospondyli.

Fig. 87.—Stomias ferox Reinhardt. Banquereau.

Astronesthidæ is another small group of small fishes naked and black, with long canines, found in the deep sea.

The Malacosteidæ is a related group with extremely distensible 129mouth, the species capable of swallowing fishes much larger than themselves.

The viper-fishes (Chauliodontidæ) are very feeble and very voracious little fishes occasionally brought up from the depths. Chauliodus sloanei is notable for the length of the fangs.

Much smaller and feebler are the species of the closely related family of Gonostomidæ. Gonostoma and Cyclothone dwell in oceanic abysses. One species, Cyclothone elongata, occurs at the depth of from half a mile to nearly four miles almost everywhere throughout the oceans. It is probably the most widely distributed, as well as one of the feeblest and most fragile, of all bassalian or deep-sea fishes.

Fig. 88.—Chauliodus sloanei Schneider. Grand Banks.

Suborder Iniomi, the Lantern-fishes.—The suborder Iniomi (ἰνίον, nape; ὤμος, shoulder) comprises soft-rayed fishes, in which the shoulder-girdle has more or less lost its completeness of structure as part of the degradation consequent on life in the abysses of the sea. These features distinguish these forms from the true Isospondyli, but only in a very few of the species have these characters been verified by actual examination of the skeleton. The mesocoracoid arch is wanting or atrophied in all of the species examined, and the orbitosphenoid is lacking, so far as known. The group thus agrees in most technical characters with the Haplomi, in which group they are placed by Dr. Boulenger. On the other hand the relationships to the Isospondyli are very close, and the Iniomi have many traits suggesting degenerate Isospondyli. The post-temporal has lost its usual hold on the skull and may touch the occiput on the sides of the cranium. Nearly all the species are soft in body, black or silvery over black in color, and all that live 130in the deep sea are provided with luminous spots or glands giving light in the abysmal depths. These spots are wanting in the few shore species, as also in those which approach most nearly to the Salmonidæ, these being presumably the most primitive of the group. In these also the post-temporal touches the back of the cranium near the side. In the majority of the Iniomi the adipose fin of the Salmonidæ is retained. From the phosphorescent spots is derived the general name of lantern-fishes applied of late years to many of the species. Most of these are of recent discovery, results of the remarkable work in deep-sea dredging begun by the Albatross and the Challenger. All of the species are carnivorous, and some, in spite of their feeble muscles, are exceedingly voracious, the mouth being armed with veritable daggers and spears.

Aulopidæ.—Most primitive of the Iniomi is the family of Aulopidæ, having an adipose fin, a normal maxillary, and no luminous spots. The rough firm scales suggest those of the berycoid fishes. The few species of Aulopus and Chlorophthalmus are found in moderate depths. Aulopus purpurissatus is the "Sergeant Baker" of the Australian fishermen.

Fig. 89.—Lizard-fish, Synodus fætens L. Charleston, S. C.

The Lizard-fishes.—The Synodontidæ, or lizard-fishes, have lizard-like heads with very large mouth. The head is scaly, a character rare among the soft-rayed fishes. The slender maxillary is grown fast to the premaxillary, and the color is not black. Most of the species are shore-fishes and some are brightly colored. Synodus fætens is the common lizard-fish, or galliwasp, of our Atlantic coast. Synodus varius of the Pacific is brightly colored, olive-green and orange-red types of coloration existing at different depths. Most of the species lie close to the bottom and are mottled gray like coral sand. A few occur in 131oceanic depths. The "Bombay duck" of the fishermen of India is a species of Harpodon, H. nehereus, with large mouth and arrow-shaped teeth. The dried fish is used as a relish.

The Benthosauridæ are deep-sea fishes of similar type, but with distinct maxillaries. The Bathypteroidæ, of the deep seas, resemble Aulopus, but have the upper and lower pectoral rays filiform, developed as organs of touch in the depths in which the small eyes become practically useless.

Ipnopidæ.—In the Ipnopidæ the head is depressed above and the two eyes are flattened and widened so as to occupy most of its upper surface. These structures were at first supposed to be luminous organs, but Professor Moseley has shown them to be eyes. "They show a flattened cornea extending along the median line of the snout, with a large retina composed of peculiar rods which form a complicated apparatus destined undoubtedly to produce an image and to receive especial luminous rays." The single species, Ipnops murrayi, is black in color and found at the depth of 2½ miles in various seas.

Fig. 90.—Ipnops murrayi Günther.

The existence of well-developed eyes among fishes destined to live in the dark abysses of the ocean seems at first contradictory, but we must remember that these singular forms are descendants of immigrants from the shore and from the surface. "In some cases the eyes have not been specially modified, but in others there have been modifications of a luminous mucous membrane leading on the one hand to phosphorescent organs more or less specialized, or on the other to such remarkable structures as the eyes of Ipnops, intermediate between true eyes and phosphorescent plates. In fishes which cannot see, and which retain for their guidance only the general sensibility of the integuments and the lateral line, these parts soon acquire a very great delicacy. The same is the case with 132tactile organs (as in Bathypterois and Benthosaurus), and experiments show that barbels may become organs of touch adapted to aquatic life, sensitive to the faintest movements or the slightest displacement, with power to give the blinded fishes full cognizance of the medium in which they live."

Rondeletiidæ.—The Rondeletiidæ are naked black fishes with small eyes, without adipose fin and without luminous spots, taken at great depths in the Atlantic. The relationship of these fishes is wholly uncertain.

Fig. 91.—Cetomimus gillii Goode & Bean. Gulf Stream.

The Cetomimidæ are near allies of the Rondeletiidæ, having the mouth excessively large, with the peculiar form seen in the right whales, which these little fishes curiously resemble.

Fig. 92.—Headlight Fish, Diaphus lucidus Goode & Bean. Gulf Stream.

Myctophidæ.—The large family of Myctophidæ, or lantern-fishes, is made up of small fishes allied to the Aulopidæ, but with the body covered with luminous dots, highly specialized and symmetrically arranged. Most of them belong to the deep sea, but others come to the surface in the night or during storms when the sunlight is absent. Through this habit they are often thrown by the waves on the decks of small vessels. 133Largely from Danish merchant-vessels, Dr. Lütken has obtained the unrivaled collection of these sea-waifs preserved in the Museum of the University of Copenhagen. The species are all small in size and feeble in structure, the prey of the larger fishes of the depths, from which their lantern-like spots and large eyes help them to escape. The numerous species are now ranged in about fifteen genera, although earlier writers placed them all in a single genus Myctophum (Scopelus).

Fig. 93.—Lantern-fish, Myctophum opalinum Goode & Bean. Gulf Stream.

In the genus Diaphus (Æthoprora) there is a large luminous gland on the end of the short snout, like the headlight of an engine. In Dasyscopelus the scales are spinescent, but in most of the genera, as in Myctophum, the scales are cycloid and caducous, falling at the touch. In Diaphus the luminous spots are crossed by a septum giving them the form of the Greek letter θ (theta). One of the commonest species is Myctophum humboldti.

Fig. 94.—Lantern-fish, Ceratoscopelus madeirensis (Lowe). Gulf Stream.

Chirothricidæ.—The remarkable extinct family of Chirothricidæ may be related to the Synodontidæ, or Myctophidæ. In this group the teeth are feeble, the paired fins much 134enlarged, and the ventrals are well forward. The dorsal fin, inserted well forward, has stout basal bones. Chirothrix libanicus of the Cretaceous of Mt. Lebanon is remarkable for its excessively large ventral fins. Telepholis is a related genus. Exocœtoides with rounded caudal fin is probably the type of a distinct family, Exocœtoididæ, the caudal fin being strongly forked in Chirothrix. The small extinct group of Rhinellidæ is usually placed near the Myctophidæ. They are distinguished by the very long gar-like jaws; whether they possessed adipose fins or luminous spots cannot be determined. Rhinellus furcatus and other species occur in the Cretaceous of Europe and Asia. Fossil forms more or less distinctly related to the Myctophidæ are numerous. Osmeroides monasterii (wrongly called Sardinioides), from the German Cretaceous, seems allied to Myctophum, although, of course, luminous spots leave no trace among fossils. Acrognathus boops is remarkable for the large size of the eyes.

Fig. 95.—Rhinellus furcatus Agassiz. Upper Cretaceous of Mt. Lebanon. (After Woodward.)

Maurolicidæ.—The Maurolicidæ are similar in form and habit, but scaleless, and with luminous spots more highly specialized. Maurolicus pennanti, the "Sleppy Argentine," is occasionally taken on either side of the Atlantic. Other genera are Zalarges, Vinciguerria, and Valenciennellus.

The Lancet-fishes.—The Plagyodontidæ (Alepisauridæ) contains the lancet-fishes, large, swift, scaleless fishes of the ocean depths with very high dorsal fin, and the mouth filled with knife-like teeth. These large fish are occasionally cast up by storms or are driven to the shores by the torments of a parasite, Tetrarhynchus, found imbedded in the flesh.

It is probable that they are sometimes killed by being forced above their level by fishes which they have swallowed. In such cases they are destroyed through the reduction of pressure.

Every part of the body is so fragile that perfect specimens are rare. The dorsal fin is readily torn, the bones are very 135feebly ossified, and the ligaments connecting the vertebræ are very loose and extensible, so that the body can be considerably stretched. "This loose connection of the parts of the body is found in numerous deep-sea fishes, and is merely the consequence of their withdrawal from the pressure of the water to which they are exposed in the depths inhabited by them. When within the limits of their natural haunts, the osseous, muscular, and fibrous parts of the body will have that solidity which is required for the rapid and powerful movements of a predatory fish. That the fishes of this genus (Plagyodus) belong to the most ferocious of the class is proved by their dentition and the contents of their stomach." (Günther.) Dr. Günther elsewhere observes: "From the stomach of one example have been taken several octopods, crustaceans, ascidians, a young Brama, twelve young boarfishes (Capros), a horse-mackerel, and one young of its own species."

Fig. 96.—Lancet-fish, Plagyodus ferox (Lowe). New York.

The lancet-fish, Plagyodus ferox, is occasionally taken on either side of the Atlantic and in Japan. The handsaw-fish, called Plagyodus æsculapius, has been taken at Unalaska, off San Luis Obispo, and in Humboldt Bay. It does not seem to differ at all from Plagyodus ferox. The original type from Unalaska had in its stomach twenty-one lumpfishes (Eumicrotremus spinosus). This is the species described from Steller's manuscripts by Pallas under the name of Plagyodus. Another species, Plagyodus borcalis, is occasionally taken in the North Pacific.

The Evermannellidæ is a small family of small deep-sea fishes 136with large teeth, distensible muscles, and an extraordinary power of swallowing other fishes, scarcely surpassed by Chiasmodon or Saccopharynx. Evermannella (Odontostomus, the latter name preoccupied) and Omosudis are the principal genera.

The Paralepidæ are reduced allies of Plagyodus, slender, silvery, with small fins and fang-like jaws. As in Plagyodus, the adipose fin is developed and there are small luminous dots. The species are few and mostly northern; one of them, Sudis ringens, is known only from a single specimen taken by the present writer from the stomach of a hake (Merluccius productus), the hake in turn swallowed whole by an albacore in the Santa Barbara Channel. The Sudis had been devoured by the hake, the hake by the albacore, and the albacore taken on the hook before the feeble Sudis had been digested.

Fig. 97.—Eurypholis sulcidens Pictet, restored. Family Enchodontidæ. Upper Cretaceous of Mt. Lebanon. (After Woodward, as E. boissieri.)

Perhaps allied to the Plagyodontidæ is also the large family of Enchodontidæ, widely represented in the Cretaceous rocks of Syria, Europe, and Kansas. The body in this group is elongate, the teeth very strong, and the dorsal fin short. Enchodus lewesiensis is found in Mount Lebanon, Halec sternbergi in the German Cretaceous, and many species of Enchodus in Kansas; Cimolichthys dirus in North Dakota.

Remotely allied to these groups is the extinct family of Dercetidæ from the Cretaceous of Germany and Syria. These are elongate fishes, the scales small or wanting, but with two or more series of bony scutes along the flanks. In Dercetis scutatus the scutes are large and the dorsal fin is very long. Other genera are Leptotrachelus and Pelargorhynchus. Dr. Boulenger places the Dercetidæ in the order Heteromi. This is an expression of the fact that their relations are still unknown. Probably 137related to the Dercetidæ is the American family of Stratodontidæ with its two genera, Stradodus and Empo from the Cretaceous (Niobrara) deposits of Kansas. Empo nepaholica is one of the best-known species.

Fig. 98.—Eurypholis freyeri Heckel. Family Enchodontidæ. Cretaceous. (After Heckel; the restoration of the jaws incorrect.)

Fig. 99.—Argyropelecus olfersi Cuvier. Gulf Stream.

The Sternoptychidæ.—The Sternoptychidæ differ materially from all these forms in the short, compressed, deep body and distorted form. The teeth are small, the body bright silvery, with luminous spots. The species live in the deep seas, rising in dark or stormy weather. Sternoptyx diaphana is found in almost all seas, and species of Argyropelecus are almost as widely distributed. After the earthquakes in 1896, which engulfed the fishing villages of Rikuzen, in northern Japan, 138numerous specimens of this species were found dead, floating on the water, by the steamer Albatross.

The Idiacanthidæ are small deep-sea fishes, eel-shaped and without pectorals, related to the Iniomi.

Order Lyopomi.—Other deep-sea fishes constitute the order or suborder Lyopomi (λυός, loose; πῶμα, opercle). These are elongate fishes having no mesocoracoid, and the preopercle rudimentary and connected only with the lower jaw, the large subopercle usurping its place. The group, which is perhaps to be regarded as a degenerate type of Isospondyli, contains the single family of Halosauridæ, with several species, black in color, soft in substance, with small teeth and long tapering tail, found in all seas. The principal genera are Halosaurus and Aldrovandia (Halosauropsis). Aldrovandia macrochira is the commonest species on our Atlantic coast.

Fig. 100.—Aldrovandia gracilis (Goode & Bean). Guadaloupe Island, West Indies. Family Halosauridæ.

Several fossil Halosauridæ are described from the Cretaceous of Europe and Syria, referred to the genera Echidnocephalus and Enchelurus. Boulenger refers the Lyopomi to the suborder Heteromi.

The Eels.—We may here break the sequence from the Isospondyli to the other soft-rayed fishes, to interpolate a large group of uncertain origin, the series or subclass of eels.

The mass of apodal or eel-like fishes has been usually regarded as constituting a single order, the Apodes (ἄ, without; ποῦς, foot). The group as a whole is characterized by the almost universal separation of the shoulder-girdle from the skull, by the absence of the mesocoracoid arch on the shoulder-girdle, by the presence of more than five pectoral actinosts, as in the Ganoid fishes, by the presence of great numbers of undifferentiated vertebræ, giving the body a snake-like form, by the absence in all living forms of the ventral fins, and, in all living forms, by the absence of a separate caudal fin. These structures indicate a low organization. Some of them are certainly results of degeneration, and others are perhaps indications of primitive simplicity. Within the limits of the group are seen other features of degeneration, notably shown in the progressive loss of the bones of the upper jaw and the membrane-bones of the head and the degradation of the various fins. The symplectic bone is wanting, the notochord is more or less persistent, the vertebral centra always complete constricted cylinders, none coalesced. But, notwithstanding great differences in these regards, the forms have been usually left in a single order, the more degraded forms being regarded as descended from the types which approach nearest to the ordinary fishes. From this view Professor Cope dissents. He recognizes several orders of eels, claiming that we should not unite all these various fishes into a single order on account of the eel-like form. If we do so, we should place in another order those with the fish-like form. 140It is probable, though not absolutely certain, that the Apodes are related to each other. The loss among them, first, of the connection of the post-temporal with the skull; second, of the separate caudal fin and its hypural support; third, of the distinct maxillary and premaxillary; and fourth, of the pectoral fins, must be regarded as successive phases of a general line of degradation. The large number of actinosts, the persistence of the notochord, the absence of spines, and the large numbers of vertebræ seem to be traits of primitive simplicity. Special lines of degeneration are further shown by deep-sea forms. What the origin of the Apodes may have been is not known with any certainty. They are soft-rayed fishes, with the air-bladder connected by a tube with the œsophagus, and with the anterior vertebræ not modified. In so far they agree with the Isospondyli. In some other respects they resemble the lower Ostariophysi, especially the electric eel and the eel-like catfishes. But these resemblances, mainly superficial, may be wholly deceptive; we have no links which certainly connect the most fish-like Apodes with any of the other orders. Probably Woodward's suggestion that they may form a series parallel with the Isospondyli and independently descended from Tertiary Ganoids deserves serious consideration. Perhaps the most satisfactory arrangement of these fishes will be to regard them as constituting four distinct orders for which we may use the names Symbranchia (including Ichthyocephali and Holostomi), Apodes (including Enchelycephali and Colocephali), Carencheli, and Lyomeri.

Order Symbranchia.—The Symbranchia are distinguished by the development of the ordinary fish mouth, the maxillary and premaxillary being well developed. The gill-openings are very small, and usually confluent below. These fresh-water forms of the tropics, however eel-like in form, may have no real affinity with the true eels. In any event, they should not be placed in the same order with the latter.

The eels of the suborder Ichthyocephali (ιχθύς, fish; κεφαλή, head) have the head distinctly fish-like. The maxillary, premaxillary, and palatines are well developed, and the shoulder-girdle is joined by a post-temporal to the skull. The body is distinctly eel-like, the tail being very short and the fins inconspicuous. 141The number of vertebræ is unusually large. The order contains the single family Monopteridæ, the rice-field eels, one species, Monopterus albus, being excessively common in pools and ditches from China and southern Japan to India.

The eels of the suborder Holostomi (ὀλός, complete; στόμα, mouth) differ from these mainly in the separation of the shoulder-girdle from the skull, a step in the direction of the true eels. The Symbranchidæ are very close to the Monopteridæ in external appearance, small, dusky, eel-like inhabitants of sluggish ponds and rivers of tropical America and the East Indies. The gill-openings are confluent under the throat. Symbranchus marmoratus ranges northward as far as Vera Cruz, having much the habit of the rice-field eel of Japan and China. The Amphipnoidæ, with peculiar respiratory structures, abound in India. Amphipnous cuchia, according to Günther, has but three gill-arches, with rudimentary lamina and very narrow slits. To supplement this insufficient branchial apparatus, a lung-like sac is developed on each side of the body behind the head, opening between the hyoid and the first branchial arch. The interior of the sac is abundantly provided with blood-vessels, the arterial coming from the branchial arch, whilst those issuing from it unite to form the aorta. Amphipnous has rudimentary scales. The other Holostomi and Ichthyocephali are naked and all lack the pectoral fin.

The Chilobranchidæ are small sea-fishes from Australia, with the tail longer than the rest of the body, instead of much shorter as in the others.

No forms allied to Symbranchus or Monopterus are recorded as fossils.

Order Apodes, or True Eels.—In this group the shoulder-girdle is free from the skull, and the bones of the jaws are reduced in number, through coalescence of the parts.

Three well-marked suborders may be recognized, groups perhaps worthy of still higher rank: Archencheli, Enchelycephali, and Colocephali.

Suborder Archencheli.—The Archencheli, now entirely extinct, are apparently the parents of the eels, having, however, certain traits characteristic of the Isospondyli. They retain the separate caudal fin, with the ordinary hypural plate, and Professor 142Hay has recently found, in an example from the Cretaceous of Mount Lebanon, remains of distinct ventral fins. These traits seem to indicate an almost perfect transition from the Isospondyli to the Archencheli.

One family may be recognized at present, Urenchelyidæ.

The earliest known eel, Urenchelys avus, occurs in the upper Cretaceous at Mount Lebanon. It represents the family Urenchelyidæ, apparently allied to the Anguillidæ, but having a separate caudal fin. Its teeth are small, conical, blunt, in many series. There are more than 100 vertebræ, the last expanded in a hypural. Pectorals present. Scales rudimentary; dorsal arising at the occiput. Branchiostegals slender, not curved around the opercle. Urenchelys anglicus is another species, found in the chalk of England.

Suborder Enchelycephali.—The suborder Enchelycephali (ἔγχελυς, eel; κεφαλή, head) contains the typical eels, in which the shoulder-girdle is free from the skull, the palatopterygoid arch relatively complete, the premaxillaries wanting or rudimentary, the ethmoid and vomer coalesced, forming the front of the upper jaw, the maxillaries lateral, and the cranium with a single condyle. In most of the species pectoral fins are present, and the cranium lacks the combined degradation and specialization shown by the morays (Colocephali).

Family Anguillidæ.—The most primitive existing family is that of the typical eels, Anguillidæ, which have rudimentary scales oblong in form, and set separately in groups at right angles with one another. These fishes are found in the fresh and brackish waters of all parts of the world, excepting the Pacific coast of North America and the islands of the Pacific. In the upper Great Lakes and the upper Mississippi they are also absent unless introduced. The species usually spawn in the sea and ascend the rivers to feed. But some individuals certainly spawn in fresh water, and none go far into the sea, or where the water is entirely salt. The young eels sometimes ascend the brooks near the sea in incredible numbers, constituting what is known in England as "eel-fairs." They will pass through wet grass to surmount ordinary obstacles. Niagara Falls they cannot pass, and according to Professor Baird "in the spring and summer the visitor who enters under the sheet of water at the foot of the 143falls will be astonished at the enormous numbers of young eels crawling over the slippery rocks and squirming in the seething whirlpools. An estimate of hundreds of wagon-loads, as seen in the course of the perilous journey referred to, would hardly be considered excessive by those who have visited the spot at a suitable season of the year." "At other times large eels may be seen on their way down-stream, although naturally they are not as conspicuous then as are the hosts of the young on their way upstream. Nevertheless it is now a well-assured fact that the eels are catadromous, that is, that the old descend the watercourses to the salt water to spawn, and the young, at least of the female sex, ascend them to enjoy life in the fresh water."

Fig. 101.—Common Eel, Anguilla chrisypa Rafinesque. Holyoke, Mass.

Reproduction of the Eel.—Dr. Gill ("Riverside Natural History," p. 103) gives the following account of the reproduction of Anguilla:

"The generation of the eel was long involved in great mystery, and the knowledge thereof is one of the recent acquisitions of scientific investigation. So late, indeed, as 1880 it was declared that 'their mode of propagation is still unknown.' In want of positive knowledge the rein has been given to loose hypothesis and conjecture. It has been variously asserted that eels were generated from slime, from dew, and from the skins of old eels or of snakes. The statement that they come from horse-hairs is familiar to many country boys, and the origin of this belief is due simply to the fact that there are certain aquatic worms, known under the generic name Gordius, which are elongated and apparently smooth like the eel, and which 144may be found in the same waters. It was one of the ideas of the Greek to attribute their paternity, as of many other doubtful offspring, to the convenient Jupiter. The statement that they are viviparous has arisen from two causes: one the existence of intestinal worms, and the other from the confusion of the eel with an elongated and consequently eel-like but otherwise very different form, the Zoarces viviparus. The Zoarces is indeed, in Germany as well as in the Scandinavian countries, generally known as the Aal-mutter, or eel-mother, and thus in its name perpetuates the fancy. Even where eels are to be found in extreme abundance, and where they are the objects of a special culture, like erroneous opinions prevail. Thus, according to Jacoby, about the lagoon of Comacchio there is an 'ineradicable belief among the fishermen that the eel is born of other fishes; they point to special differences in color and especially in the common mullet, Mugil cephalus, as the causes of variation in color and form among eels. It is a very ancient belief, widely prevalent to the present day, that eels pair with water-snakes. In Sardinia the fishermen cling to the belief that a certain beetle, the so-called water-beetle, Dytiscus ræselii, is the progenitor of eels, and they therefore call this "mother of eels."' The assignment of such maternity to the water-beetle is doubtless due to the detection of the hair-worm, or Gordius, in the insect by sharp-sighted but unscientific observers, and, inasmuch as the beetle inhabits the same waters as the eel, a very illogical deduction has led to connect the two together.

"All such beliefs as have been thus recounted are due to the inconspicuous nature of the generative organs in eels found in fresh waters and at most seasons—a characteristic which is in strong contrast to the development of corresponding parts in fishes generally. Nevertheless the ovaries of the eel were discovered, as long ago as 1707, by Dr. Sancassini of Comacchio, and described by the celebrated Valisneri (after whom the plant Valisneria was named) in 1710, again by Mondini in 1777, and almost contemporaneously by O. J. Müller of Denmark. Later the illustrious Rathke (in 1824, 1838, and 1850) and also Hornbaum-Hornschuch published the results of special investigations, and figured the eggs. But it was only in 1873 (after several futile endeavors by others) that the male organ 145of the eel was recognized, also by an Italian naturalist, Dr. Syrski, in small individuals of the species, and a previous idea that the eel was hermaphroditic thereby dispelled. The sexual differences are correlated with external ones, and generally the males and females, when adult, can be told apart. Jacoby testifies that he examined large numbers with a view to solve this question. The most important differences relate to (1) size; (2) form of the snout; (3) color; (4) dorsal fin; and (5) size of the eyes. (1) The males rarely attain a length of more than seventeen to nineteen inches, while adult females are generally much larger; (2) the snout in the male is attenuated and rather pointed, while in the female it is comparatively broad and blunt; (3) the male is of a deep darkish green, or often a deep black with a shining luster and a whitish belly, while the female has a clearer color, usually of a greenish hue on the back and yellowish on the belly; (4) the dorsal fin is lower and less developed in the male than in the female; and (5) the eye of the male is large and that of the female, as a rule, comparatively small. These characters, however, do not always hold good. Jacoby remarked that 'special reference having been paid to the height and narrowness of the dorsal fin, much success has been met with in picking out, in the fish-market of Trieste, the eels which possessed the organ of Syrski (that is, the male organ); absolute certainty, however, in recognizing them cannot be guaranteed. If one is searching among living eels with no characters in mind,—with the exception of the first, that of length,—he will find in every ten eels, on an average, eight females and two with the supposed male organ; but if the selection is made with a careful reference to all these marks of difference, the proportion changes, and out of every ten examples about eight will be found with the supposed male organ.'

"According to Herr Benecke, 'it may be assumed with the greatest safety that the eel lays its eggs like most other fish, and that, like the lamprey, it spawns only once and then dies. All the eggs of a female show the same degree of maturity, while in the fish which spawn every year, besides the large eggs which are ready to be deposited at the next spawning period, there exist very many of much smaller size, which are 146destined to mature hereafter and be deposited in other years. It is very hard to understand how young eels could find room in the body of their mother if they were retained until they had gained any considerable size. The eel embryo can live and grow for a long time supported by the little yolk, but, when this is done, it can only obtain food outside of the body of its mother. The following circumstances lead us to believe that the spawning of the eel takes place only in the sea: (1) that the male eel is found only in the sea or brackish water, while female eels yearly undertake a pilgrimage from the inland waters to the sea, a circumstance which has been known since the time of Aristotle, and upon the knowledge of which the principal capture of eels by the use of fixed apparatus is dependent; (2) that the young eels, with the greatest regularity, ascend from the sea into the rivers and lakes.'"

All statements in opposition to this theory are untenable, since the young eels never find their way into landlocked ponds in the course of their wanderings, while eels planted in such isolated bodies of water thrive and grow rapidly, but never increase in numbers. Another still more convincing argument is the fact that in lakes which formerly contained many eels, but which, by the erection of impassable weirs, have been cut off from the sea, the supply of eels has diminished, and after a time only scattering individuals, old and of great size, are taken in them. An instance of this sort occurred in Lake Muskengorf in West Prussia. If an instance of the reproduction of the eel in fresh water could be found, such occurrences as these would be quite inexplicable.

In the upper stretches of long rivers the migration of the eels begins in April or in May; in their lower stretches and shorter streams, later in the season. In all running waters the eel-fishery depends upon the downward migrations; the eels press up the streams with occasional halts, remaining here and there for short periods, but always make their way above. They appear to make the most progress during dark nights, when the water is troubled and stormy, for at this time they are captured in the greatest numbers. It is probable that after the eels have once returned to the sea and there deposited their spawn, they never can return into fresh water, but remain 147there to die. A great migration of grown eels in spring or summer has never been reported, and it appears certain that all the female eels which have once found their way to the sea are lost to the fisherman.

Food of the Eel.—Eels, in the words of Mr. W. H. Ballou, are "among the most voracious of carnivorous fishes. They eat most inland fishes, except the garfish and the chub. Investigation of six hundred stomachs by Oswego fishermen showed that the latter bony fish never had a place in their bill of fare. They are particularly fond of game-fishes, and show the delicate taste of a connoisseur in their selection from choice trout, bass, pickerel, and shad. They fear not to attack any object when disposed, and their bite in human flesh shows even a vicious attitude towards man. On their hunting excursions they overturn huge and small stones alike, working for hours if necessary, beneath which they find species of shrimp and crayfish, of which they are exceedingly fond. Of shrimps they devour vast numbers. Their noses are poked into every imaginable hole in their search for food, to the terror of innumerable small fishes."

In the opinion of Mr. Ballou, too, "eels are to the water what the fishhawk is to the air. They are, perhaps, the most powerful and rapid of natatorians. Again, they hide in the mud beneath some log or overhanging rock, and dart out with tremendous fury at the unsuspecting prey. They attack the spawn of other fishes open-mouthed, and are even said to suck the eggs from an impaled female. They fearlessly and rapidly dive head-foremost in the mud, disappearing from view in the twinkling of a star. They are owl-like in their habits, committing many of their depredations at night.

"No fish is yet reported to utilize a full-grown eel as food. Pickerel, garfish, and bass, which are particularly numerous in these lakes, are supposed to literally devour the young fry. Mr. Sawyer describes the operation of the pickerel darting through a long column of young eels open-mouthed and devouring vast numbers of them."

Larva of the Eel.—The translucent band-shaped larva of the common eel has been very recently identified and described by Dr. Eigenmann. It is probable that all true eels, Enchelycephali, 148pass through a band-shaped or leptocephalous stage, as is the case with Albula and other Isospondyli. In the continued growth the body becomes firmer, and at the same time much shorter and thicker, gradually assuming the normal form of the species in question.

Fig. 102.—Larva of Common Eel, Anguilla chrisypa (Rafinesque), called Leptocephalus grassii. (After Eigenmann.)

In a recent paper Dr. Carl H. Eigenmann has very fully reviewed the life-history of the eel. The common species live in fresh waters, migrating to the sea in the winter. They deposit in deep water minute eggs that float at the surface. The next year they develop into the band-shaped larva. The young eels enter the streams two years after their parents drop down to the sea. It is doubtful whether eels breed in fresh water. The male eel is much smaller than the female.

The eel is an excellent food-fish, the flesh being tender and oily, of agreeable flavor, better than that of any of its relatives. Eels often reach a large size, old individuals of five or six feet in length being sometimes taken.

Species of Eels.—The different species are very closely related. Not more than four or five of them are sharply defined, and these mostly in the South Seas and in the East Indies. The three abundant species of the north temperate zone, Anguilla anguilla of Europe, Anguilla chrisypa of the eastern United States, and Anguilla japonica of Japan, are scarcely distinguishable. In color, size, form, and value as food they are all alike.

Fossil species referred to the Anguillidæ are known from the early Tertiary. Anguilla leptoptera occurs in the Eocene of Monte Bolea, and Anguilla elegans in the Miocene of Œningen in Baden. Other fossil eels seem to belong to the Nettastomidæ and Myridæ.

Pug-nosed Eels.—Allied to the true eel is the pug-nosed eel, Simenchelys parasiticus, constituting the family of Simenchelyidæ. This species is scaled like a true eel, has a short, 149blunt nose, and burrows its way into the bodies of halibut and other large fishes. It has been found in Newfoundland and Madeira. Another family possessing rudimentary scales is that of the Synaphobranchidæ, slender eels of the ocean depths, widely distributed. In these forms the gill-openings are confluent. Synaphobranchus pinnatus is the best-known species.

Fig. 103.—Pug-nosed Eel, Simenchelys parasiticus Gill. Sable Island Bank.

Fig. 104.—Synaphobranchus pinnatus (Gronow). Le Have Bank.

Conger-eels.—The Leptocephalidæ, or conger-eels, are very similar to the fresh-water eels, but are without scales and with a somewhat different mouth, the dorsal beginning nearer to the head.

The principal genus is Leptocephalus, including the common conger-eel (Leptocephalus conger) of eastern America and Europe and numerous very similar species in the tropics of both continents. These fishes are strictly marine and, reaching the length of five or six feet, are much valued as food. The eggs are much larger than those of the eel and are produced in great numbers, so that the female almost bursts with their numbers. Dr. Hermes calculated that 3,300,000 were laid by one female in an aquarium.

These eggs hatch out into transparent band-like larva, with very small heads formerly known as Leptocephalus, an ancient name which is now taken for the genus of congers, having 150been first used for the larva of the common conger-eel. The loose watery tissues of these "ghost-fishes" grow more and more compact and they are finally transformed into young congers.

Fig. 105.—Conger-eel, Leptocephalus conger (L.). Noank, Conn.

The Murænesocidæ are large eels remarkable for their strong knife-like teeth. Murænesox savanna occurs in the West Indies and in the Mediterranean, Murænesox cinereus in Japan, and Murænesox coniceps on the west coast of Mexico, all large and fierce, with teeth like shears. The Myridæ are small and worm-like eels closely allied to the congers, having the tail surrounded by a fin, but the nostrils labial. Myrus myrus is found in the Mediterranean. Species of Eomyrus, Rhynchorhinus, and Paranguilla apparently allied to Myrus occur in the Eocene. Other related families, mostly rare or living in the deep seas, are the Ilyophidæ, Heterocongridæ, and Dysommidæ.

Fig. 106.—Larva of Conger-eel (Leptocephalus conger), called Leptocephalus morrissi. (After Eigenmann.)

The Snake-eels.—Most varied of the families of eels is the Ophichthyidæ, snake-like eels recognizable by the form of the tail, which protrudes beyond the fins. Of the many genera found in tropical waters several are remarkable for the sharply defined coloration, suggesting that of the snake. Characteristic species are Chlevastes colubrinus and Leiuranus semicinctus, two beautifully banded species of Polynesia, living in the same holes in the reefs and colored in the same fashion. Another is Callechelys 151melanotænia. The commonest species on the Atlantic coast is the plainly colored Ophichthus gomesi.

Fig 107.—Xyrias revulsus Jordan & Snyder. Family Ophichthyidæ. Misaki, Japan.

In the genus Sphagebranchus, very slender eels of the reefs, the fins are almost wanting.

Fig. 108.—Myrichthys pantostigmius Jordan & McGregor. Clarion Island.

Fig. 109.—Ophichthus ocellatus (Le Sueur). Pensacola.

Allied to the Congers is the small family of duck-billed eels (Nettastomidæ) inhabiting moderate depths of the sea. Nettastoma bolcense occurs in the Eocene of Monte Bolca. The produced snout forms a transition to the really extraordinary type of thread-eels or snipe-eels (Nemichthyidæ), of which numerous genera and species live in the oceanic depths. In Nemichthys the long, very slender, needle-like jaws are each curved backward so that the mouth cannot by any possibility be shut. The body is excessively slender and the fish swims with swift undulations, often near the surface, and when seen is usually 152taken for a snake. The best-known species is Nemichthys scolopaceus of the Atlantic and Pacific. Nemichthys avocetta, very much like it, has been twice taken in Puget Sound.

Fig. 110.—Thread-eel, Nemichthys avocetta Jordan & Gilbert. Vancouver Island.

Suborder Colocephali, or Morays.—In the suborder Colocephali (κολός, deficient; κεφαλή, head) the palatopterygoid arch and the membrane-bones generally are very rudimentary. The skull is thus very narrow, the gill-structures are not well developed, and in the chief family there are no pectoral fins. This group is very closely related to the Enchelycephali, from which it is probably derived.

Fig. 111.—Jaws of Nemichthys avocetta Jordan & Gilbert.

In the great family of morays (Murænidæ) the teeth are often very highly developed. The muscles are always very strong and the spines bite savagely, a live moray being often able to drive men out of a boat. The skin is thick and leathery, and the coloration is highly specialized, the pattern of color being often elaborate and brilliant. In Echidna zebra for example the body is wine-brown, with cross-stripes of golden yellow. In Muræna each nostril has a barbel. Muræna helena, the oldest moray known, is found in Europe. In Gymnothorax, the largest genus, only the anterior nostrils are thus provided. Gymnothorax mordax of California is a large food-fish, as are also the brown Gymnothorax funebris and the spotted Gymnothorax moringa in the West Indies. These and many other species may coil themselves in crevices in the reefs, whence they strike out at their prey like snakes, taking perhaps the head of a duck or the finger of a man.

153In many of the morays the jaws are so curved and the mouth so filled with knife-like teeth that the jaws cannot be closed. This fact, however, renders no assistance to their prey, as the teeth are adapted for holding as well as for cutting.

In Enchelynassa bleekeri, a huge wine-colored eel of the South Seas, the teeth are larger than in any other species. Evenchelys (macrurus) is remarkable for its extraordinary length of tail, Echidna for its blunt teeth, and Scuticaria, Uropterygius, and Channomuræna for the almost complete absence of fins. In Anarchias (allardicei; knighti), the anal fin is absent. The flesh of the morays is rather agreeable in taste, but usually oily and not readily digestible, less wholesome than that of the true eels.

Fig. 112.—Muræna retifera Garman. Charleston, S. C.

The Myrocongridæ are small morays with developed pectoral fins. The species are few and little known.

Family Moringuidæ.—Structurally one of the most peculiar of the groups of eels is the small family of Moringuidæ of the East and West Indies. In these very slender, almost worm-like fishes the heart is placed very far behind the gills and the tail is very short. The fins are very little developed, and some forms, as Gordiichthys irretitus of the Gulf of Mexico, the body as slender as a whiplash, possess a very great number of vertebræ. Moringua hawaiiensis occurs in Hawaii, M. edwardsi in the Bahamas. This family probably belongs with the morays to the group of Colocephali, although its real relationships are not wholly certain.

Order Carencheli, the Long-necked Eels.—Certain offshoots from the Apodes so widely diverging in structure that they must apparently be considered as distinct orders occur sparingly in the deep seas. One of these, Derichthys serpentinus, the long-necked eel, constitutes the sole known species of the suborder Carencheli (καρά, head; ἔγχελυς, eel). In this group the premaxillaries and maxillaries are present as in ordinary fishes, but united by suture and soldered to the cranium. As in true eels, the shoulder-girdle is remote from the skull. The head is set on a snake-like neck. The single species representing the family Derichthyidæ was found in the abysmal depths of the Gulf Stream.

154

Fig. 113.—Gymnothorax berndti Snyder. Hawaii. Family Murænidæ.

155

Fig. 114.—Gymnothorax jordani (Evermann & Marsh). Family Murænidæ. Puerto Rico.

Fig. 115.—Moray, Gymnothorax moringa Bloch. Family Murænidæ. Tortugas.

156

Fig. 116.—Derichthys serpentinus Gill. Gulf Stream.

Fig. 117.—Gulper-eel, Gastrostomus bairdi Gill & Ryder. Gulf Stream.

Order Lyomeri, or Gulpers.—Still more aberrent and in many respects extraordinary are the eels of the order or suborder Lyomeri (λυός, loose; μέρος, part), known as "Gulpers." These are degenerate forms, possibly degraded from some conger-like type, but characterized by an extreme looseness of structure unique among fishes. The gill-arches are reduced to five small bars of bone, not attached to the skull, the palatopterygoid arch is wholly wanting, the premaxillaries are wanting, as in all true eels, and the maxillaries loosely joined to the skull. The symplectic bone is wanting, and the lower jaw is so hinged to the skull that it swings freely in various directions. In place of the lateral line are singular appendages. Dr. Gill says of these fishes: "The entire organization is peculiar to the extent of anomaly, and our old conceptions of the characteristics of a fish require to be modified in the light of our knowledge of such strange beings." Special features are the extraordinary size of the mouth, which has a cavity larger than that of the rest of the body, the insertion of the very small eye at the tip of the snout, and the relative length of the tail. The whole substance is excessively fragile as usual with animals living in great depths and the color is jet black. Three species have been described, and these have been placed in two families, Saccopharyngidæ, with the trunk (gill-opening to the vent) much longer than the head, and Eurypharyngidæ, with the trunk very short, much shorter than the head. The best-known species is the pelican eel (Eurypharynx pelacanoides), of the coast of Morocco, described by Vaillant in 1882. Gastrostomus bairdi, very much like it, occurs in the great depths under the Gulf Stream. So fragile and so easily distorted are these fishes that 157it is possible that all three are really the same species, for which the oldest name would be Saccopharynx ampullaceus. Of this form four specimens have been taken in the Atlantic, one of them six feet long, carried to the surface through having swallowed fishes too large to be controlled. To be carried above its depth in a struggle with its prey is one of the greatest dangers to which the abysmal fishes are subject.

Order Heteromi.—The order of Heteromi (ἑτερός, different; ὤμος, shoulder), or spiny eels, may be here noticed for want of a better place, as its affinities are very uncertain. Some writers have regarded it as allied to the eels; some have placed it among the Ganoids. Others have found affinities with the sticklebacks, and still others with the singular fresh-water fishes called Mastacembelus. The Heteromi agree with the eels, as well as with Mastacembelus, in having the scapular arch separate from the cranium. Unlike all the true eels, most of the species have true dorsal and anal spines, as in the Percesoces and Hemibranchii. The ventral fins, when present, are abdominal and each with several spines in front, a character not found among the Acanthopteri. There is no mesocoracoid.

The air-bladder has a duct, and the coracoids, much as in the Xenomi, are reduced to a single lamellar imperforate plate. The two groups have little else in common, however, and this trait is possibly primitive in both cases, more likely to have arisen through independent degeneration. The separation of the shoulder-girdle doubtless indicates no affinity with the eels, as the bones of the jaws are quite normal. Two families are known, both from the deep sea, besides an extinct family in which spines are not developed.

The Notacanthidæ are elongate, compressed, ending in a band-shaped, tapering tail; the back has numerous free spines and few or no soft rays, and the mouth is normal, provided with teeth. The species of Notacanthus are few and scantily preserved. Those of Macdonaldia are more abundant. Macdonaldia challengeri is from the North Pacific, being once taken off Tokio. The extinct family of Protonotacanthidæ differs in the total absence of dorsal spines and fin-rays; the single species, Pronotocanthus sahel-almæ, originally described as a primitive eel, occurs in the Cretaceous of Mount Lebanon.

158The Lipogenyidæ have a round, sucker-like mouth, with imperfect lower jaw, but are otherwise similar. Lipogenys gilli was dredged in the Gulf Stream.

Fig. 118.—Notacanthus phasganorus Goode & Bean. Grand Banks.

Dr. Boulenger has recently extended the group of Heteromi by the addition of the Dercetidæ, Halosauridæ (Lyopomi), and the Fierasferidæ. We can hardly suppose that all these forms are really allied to Notacanthus.

Ostariophysi.—A large group of orders, certainly of common descent, may be brought together under the general name of Ostariophysi (ὀσταρίον, a small bone; θυσός, inflated). These are in many ways allied to the Isospondyli, but they have undergone great changes of structure, some of the species being highly specialized, others variously degenerate. A chief character is shared by all the species. The anterior vertebræ are enlarged, interlocked, considerably modified, and through them a series of small bones connect the air-bladder with the ear. The air-bladder thus becomes apparently an organ of hearing through a form of connection which is lost in all the higher fishes.

In all the members of this group excepting perhaps the degraded eel-like forms called Gymnonoti, the mesocoracoid arch persists, a trait found in all the living types of Ganoids, as well as in the Teleost order of Isospondyli. Other traits of the Ostariophysan fishes are shared by the Isospondyli (herring, salmon) and other soft-rayed fishes. The air-bladder is large, but not cellular. It leads through life by an open duct to the œsophagus. The ventral fins are abdominal in position. The pectorals are inserted low. A mesocoracoid arch is developed on the inner side of the shoulder-girdle. (See Fig. 119.) There are no spines on the fins, except in many cases a single one, a modified soft ray at front of dorsal or pectoral. The scales, if present, are cycloid or replaced by bony plates.

Many of the species have an armature much like that of the sturgeon, but here the resemblance ends, the bony plates in the two cases being without doubt independently evolved. According to Cope, the affinities of the catfishes to the sturgeon are "seen in the absence of symplectic, the rudimentary maxillary 160bone, and, as observed by Parker, in the interclavicles. There is also a superficial resemblance in the dermal bones." But it is not likely that any real affinity exists.

Fig. 119.—Inner view of shoulder-girdle of the Buffalo-fish. Ictiobus bubalus Rafinesque, showing the mesocoracoid (59). (After Starks.)

The sturgeons lack the characteristic auditory ossicles, or "Weberian apparatus," which the catfishes possess in common with the carp family, the Characins, and the Gymnonoti. These orders must at least have a common origin, although this origin is obscure, and fossil remains give little help to the solution of the problem. Probably the ancestors of the Ostariophysi are to be found among the allies of the Osteoglossidæ. Gill has called attention to the resemblance of Erythrinus to Amia. In any event, all the Ostariophysi must be considered together, as it is not conceivable that so complex a structure as the Weberian apparatus should have been more than once independently evolved. The branchiostegals, numerous among the Isospondyli, are mostly few among the Ostariophysi.

Fig. 120.—Weberian apparatus and air-bladder of Carp. (From Günther, after Weber.)

To the Ostariophysi belong the vast majority of the fresh-water fishes of the world. Their primitive structure is shown in many ways; among others by the large number of vertebræ instead of the usual twenty-four among the more highly specialized families of fishes. We may group the Ostariophysi under 161four orders: Heterognathi, Eventognathi (Plectospondyli), Nematognathi, and Gymnonoti.

The Heterognathi.—Of these the order of Heterognathi seems to be the most primitive, but in some ways the most highly developed, showing fewer traits of degeneration than any of the others. The presence of the adipose fin in this group and in the catfishes seems to indicate some sort of real affinity with the salmon-like forms, although there has been great change in other regards.

The order Heterognathi, or Characini (ἕτερος, different; γνάθος, jaw), contains those Ostariophysi which retain the mesocoracoid and are not eel-like, and which have the lower pharyngeals developed as in ordinary fishes. In most cases an adipose fin is present and there are strong teeth in the jaws. There are no pseudobranchiæ, and, as in the Cyprinidæ, usually but three branchiostegals. The Characidæ constitute the majority of the fresh-water fishes in those regions which have neither Cyprinidæ nor Salmonidæ. Nearly four hundred species are known from the rivers of South America and Africa. A single species, Tetragonopterus argentatus, extends its range northward to the Rio Grande in Texas. None are found in Asia, Europe, or, with this single exception, in the United States. Most of them are small fishes with deep bodies and very sharp, serrated, incisor-like teeth. Some are as innocuous as minnows, which they very much resemble, but others are extremely voracious and destructive in the highest degree. Of the caribe, belonging to the genus Serrasalmo, known by its serrated belly, Dr. Günther observes:

"Their voracity, fearlessness and number render them a perfect pest in many rivers of tropical America. In all the teeth are strong, short, sharp, sometimes lobed incisors, arranged in one or more series; by means of them they cut off a mouthful of flesh as with a pair of scissors; and any animal falling into the water where these fish abound is immediately attacked and cut to pieces in an incredibly short time. They assail persons entering the water, inflicting dangerous wounds before the victims are able to make their escape. In some localities it is scarcely possible to catch fishes with the hook and line, as the fish hooked is immediately attacked by the 'caribe' (as 162these fish are called), and torn to pieces before it can be withdrawn from the water. The caribes themselves are rarely hooked, as they snap the hook or cut the line. The smell of blood is said to attract at once thousands of these fishes to the spot."

Two families of Heterognathi are recognized: the Erythrinidæ, which lack the adipose fin, and the Characidæ, in which this fin is developed. The Erythrinidæ are large pike-like fishes of the South American rivers, robust and tenacious of life, with large mouths armed with strong unequal teeth. The best-known species is the Trahira (Hoplias malabaricus).

Fig. 121.—Brycon dentex Günther. Family Characidæ. Nicaragua.

Among the Characidæ, Serrasalmo has been already noticed. Citharinus in Africa has very few teeth, and Curimatus in South America none at all. Nannocharax in Africa is composed of very diminutive fishes, Hydrocyon exceedingly voracious ones, reaching a length of four feet, with savage teeth. Many of the species are allies of Tetragonopterus, small, silvery, bream-like fishes with flat bodies and serrated incisor teeth. Most of these are American. A related genus is Brycon, found in the streams about the Isthmus of Panama.

Extinct Characins are very rare. Two species from the Tertiary lignite of São Paulo, Brazil, have been referred to Tetragonopterus—T. avus and T. ligniticus.

The Eventognathi.—The Eventognathi (ἔυ, well; ἔν, within; γνάθος, jaw) are characterized by the absence of teeth in the jaws and by the high degree of specialization of the lower pharyngeals, 163which are scythe-shaped and in typical forms are armed with a relatively small number of highly specialized teeth of peculiar shape and arranged in one, two, or three rows. In all the species the gill-openings are restricted to the sides; there is no adipose fin, and the broad, flat branchiostegals are but three in number. In all the species the scales, if present, are cycloid, and the ventral fins, of course, abdominal. The modification of the four anterior vertebræ and their connection with the air bladder are essentially as seen in the catfishes.

The name Plectospondyli is often used for this group (πλεκτός, interwoven; σπόνδυλος, vertebra), but that term originally included the Characins as well.

Fig. 122.—Pharyngeal bones and teeth of European Chub, Leuciscus cephalus (Linnæus). (After Seelye.)

The Cyprinidæ.—The chief family of the Eventognathi and the largest of all the families of fishes is that of Cyprinidæ, comprising 200 genera and over 2000 species, found throughout the north temperate zone but not extending to the Arctic Circle on the north, nor much beyond the Tropic of Cancer on the south. In this family belong all the fishes known as carp, dace, chub, roach, bleak, minnow, bream, and shiner. The essential character of the family lies in the presence of one, two, or three rows of highly specialized teeth on the lower pharyngeals, the main row containing 4, 5, 6, or 7 teeth, the others 1 to 3. The teeth of the main row differ in form according to the food of the fish. They may be coarse and blunt, molar-like in those which feed on shells; 164they may be hooked at tip in those which eat smaller fishes; they may be serrated or not; they may have an excavated "grinding surface," which is most developed in the species which feed on mud and have long intestines. In the Cyprinidæ, or carp family, the barbels are small or wanting, the head is naked, the caudal fin forked, the mouth is toothless and without sucking lips, and the premaxillaries form its entire margin. With a few exceptions the Cyprinidæ are small and feeble fishes. They form most of the food of the predatory river fishes, and their great abundance in competition with these is due to their fecundity and their insignificance. They spawn profusely and find everywhere an abundance of food. Often they check the increase of predatory fish by the destruction of their eggs.

In many of the genera the breeding color of the males is very brilliant, rendering these little creatures for a time the most beautifully colored of fishes. In spring and early summer the fins, sides, and head in the males are often charged with pigment, the prevailing color of which is rosy, though often satin-white, orange, crimson, yellow, greenish, or jet black. Among American genera Chrosomus, Notropis, and Rhinichthys are most highly colored. Rhodeus, Rutilus, and Zacco in the Old World are also often very brilliant.

Fig. 123.—Black-nosed Dace, Rhinichthys dulcis Girard. Yellowstone River.

In very many species, especially in America, the male in the breeding season is often more or less covered with small, grayish tubercles or pearly bodies, outgrowths of the epidermis. These are most numerous on the head and fall off after the breeding season. They are most developed in Campostoma.

The Cyprinidæ are little valued as food-fishes. The carp, largely domesticated in small ponds for food, is coarse and 165tasteless. Most of the others are flavorless and full of small bones. One species, Opsariichthys uncirostris, of Japan is an exception in this regard, being a fish of very delicate flavor.

Fig. 124.—White Chub, Notropis hudsonius (Clinton). Kilpatrick Lake, Minn.

Fig. 125.—Silver-jaw Minnow, Ericymba buccata Cope. Defiance, Ohio.

In America 225 species of Cyprinidæ are known. One hundred of these are now usually held to form the single genus Notropis. This includes the smaller and weaker species, from two to seven inches in length, characterized by the loss, mostly through degeneration, of special peculiarities of mouth, fins, and teeth. These have no barbels and never more than four teeth in the main row. Few, if any, Asiatic species have so small a number, and in most of these the maxillary still retains its rudimentary barbel. But one American genus (Orthodon) has more than five teeth in the main row and none have more than two rows or more than two teeth in the lower row. By these and other peculiarities it would seem that the American species are at once less primitive and less complex than the Old World 166forms. There is some evidence that the group is derived from Asia through western America, the Pacific Coast forms being much nearer the Old World types than the forms inhabiting the Mississippi Valley. Not many Cyprinidæ are found in Mexico, none in Cuba, South America, Australia, Africa, or the islands to the eastward of Borneo. Many species are very widely distributed, many others extremely local. In the genus Notropis, each river basin in the Southern States has its series of different and mostly highly colored species. The presence of Notropis niveus in the Neuse, Notropis pyrrhomelas in the Santee, Notropis zonistius in the Chattahoochee, Notropis callistius, trichroistius, and stigmaturus in the Alabama, Notropis whipplei in the Mississippi, Notropis galacturus in the Tennessee, and Notropis cercostigma in the Sabine forms an instructive series in this regard. These fishes and the darters (Etheostominæ) are, among American fishes, the groups best suited for the study of local problems in distribution.

Fig. 126.—Silverfin, Notropis whipplei (Girard). White River, Indiana. Family Cyprinidæ.

Species of Dace and Shiner.—Noteworthy species in other genera are the following:

Largest and best known of the species of Notropis is the familiar shiner or redfin, Notropis cornutus, found in almost every brook throughout the region east of the Missouri River.

Campostoma anomalum, the stone-roller, has the very long intestines six times the length of its body, arranged in fifteen coils around the air-bladder. This species feeds on mud and spawns in little brooks, swarming in early spring throughout 167the Mississippi Valley, and is notable for its nuptial tubercles and the black and orange fins.

Fig. 127.—Stone-roller, Campostoma anomalum (Rafinesque). Family Cyprinidæ. Showing nuptial tubercles and intestines coiled about the air-bladder.

In the negro-chub, Exoglossum maxillingua of the Pennsylvanian district, the rami of the lower jaw are united for their whole length, looking like a projecting tongue.

Fig. 128.—Head of Day-chub, Exoglossum maxillingua (Le Sueur). Shenandoah River.

The fallfish, Semotilus corporalis, is the largest chub of the Eastern rivers, 18 inches long, living in swift, clear rivers. It is a soft fish, and according to Thoreau "it tastes like brown paper salted" when it is cooked. Close to this is the horned dace, Semotilus atromaculatus, and the horny head, Hybopsis kentuckiensis, both among the most widely distributed of our river fishes. These are all allied to the gudgeon (Gobio gobio), a common boys' fish of the rivers of Europe, and much sought by anglers who can get nothing better. The bream, Abramis, represented by numerous species in Europe, has a deep compressed body and a very long anal fin. It is also well represented in America, the golden shiner, common in Eastern and Southern streams, being Abramis chrysoleucus. The bleak of Europe (Alburnus alburnus) is a "shiner" close to some of our species of Notropis, while the minnow of Europe, Phoxinus phoxinus, resembles our gorgeously colored Chrosomus erythrogaster. 168Other European forms are the roach (Rutilus rutilus), the chub (Leuciscus cephalus), the dace (Leuciscus leuciscus), the id (Idus idus), the redeye (Scardinius erythropthalmus), and the tench (Tinca tinca). The tench is the largest of the European species, and its virtues with those of its more or less insignificant allies are set forth in the pages of Izaak Walton. All of these receive more attention from anglers in England than their relatives receive in America. All the American Cyprinidæ are ranked as "boys' fish," and those who seek the trout or black bass or even the perch or crappie will not notice them. Thoreau speaks of the boy who treasures the yellow perch as a real fish: "So many unquestionable fish he counts, then so many chubs which he counts, then throws away."

Fig. 129.—Horned Dace, Semotilus atromaculatus (Mitchill). Aux Plaines River, Ill. Family Cyprinidæ.

Fig. 130.—Shiner, Abramis chrysoleucus (Mitchill). Hackensack River, N. J.

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Fig. 131.—The Squawfish, Ptychocheilus grandis Agassiz. (Photograph by Cloudsley Rutter.)

Chubs of the Pacific Slope.—In the Western waters are numerous genera, some of the species reaching a large size. The species of squawfish (Ptychocheilus lucius in the Colorado, Ptychocheilus grandis in the Sacramento, and Ptychocheilus oregonensis in the Columbia) reach a length of 4 or 5 feet or even more. These fishes are long and slender, with large toothless mouths and the aspect of a pike.

Allied to these are the "hard tails" (Gila elegans and Gila robusta) of the Colorado Basin, strange-looking fishes scarcely eatable, with lean bodies, flat heads, and expanded tails. The split-tail, Pogonichthys macrolepidotus, is found in the Sacramento.

Fig. 132.—Chub of the Great Basin, Leuciscus lineatus (Girard). Heart Lake, Yellowstone Park. Family Cyprinidæ.

In the chisel-mouth, Acrocheilus alutaceus, of the Columbia the lips have a hard cutting edge. In Meda, very small fishes of the Colorado Basin, the dorsal has a compound spine of peculiar structure. Many of the species of Western waters belong to the genus Leuciscus, which includes also many species 170of Asia and Europe. The common Japanese dace (Leuciscus hakuensis) is often found out in the sea, but, in general, Cyprinidæ are only found in fresh waters. The genus of barbels (Barbus) contains many large species in Europe and Asia. In these the barbel is better developed than in most other genera, a character which seems to indicate a primitive organization. Barbus mosal of the mountains of India is said to reach a length of more than six feet and to have "scales as large as the palm of the hand."

The Carp and Goldfish.—In the American and European Cyprinidæ the dorsal fin is few-rayed, but in many Asiatic species it is longer, having 15 to 20 rays and is often preceded by a serrated spine like that of a catfish. Of the species with long dorsal the one most celebrated is the carp (Cyprinus carpio). This fish is a native of the rivers of China, where it has been domesticated for centuries. Nearly three hundred years ago it was brought to northern Europe, where it has multiplied in domestication and become naturalized in many streams and ponds. Of late years the cultivation of the carp has attracted much attention in America. It has been generally satisfactory where the nature of the fish is understood and where expectations have not been too high.

The carp is a dull and sluggish fish, preferring shaded, tranquil, and weedy waters with muddy bottoms. Its food consists of water insects and other small animals, and vegetable matter, such as the leaves of aquatic plants. They can be fed on much the same things as pigs and chickens, and they bear much the same relation to trout and bass that pigs and chickens do to wild game and game-birds. The carp is a very hardy fish, grows rapidly, and has immense fecundity, 700,000 eggs having been found in the ovaries of a single individual. It reaches sometimes a weight of 30 to 40 pounds. As a food-fish the carp cannot be said to hold a high place. It is tolerated in the absence of better fish.

The carp, either native or in domestication, has many enemies. In America, catfish, sunfish, and pike prey upon its eggs or its young, as well as water-snakes, turtles, kingfishes, crayfishes, and many other creatures which live about our ponds and in sluggish streams. In domestication numerous varieties 171of carp have been formed, the "leather-carp" (Lederkarpfen) being scaleless, others, "mirror-carp" (Spiegelkarpfen), having rows of large scales only along the lateral line or the bases of the fins.

Closely allied to the carp is the goldfish (Carassius auratus). This is also a common Chinese fish introduced in domestication into Europe and America. The golden-yellow color is found only in domesticated specimens, and is retained by artificial selection. The native goldfish is olivaceous in color, and where the species has become naturalized (as in the Potomac River, where it has escaped from fountains in Washington) it reverts to its natural greenish hue. The same change occurs in the rivers of Japan. The goldfish is valued solely for its bright colors as an ornamental fish. It has no beauty of form nor any interesting habits, and many of our native fishes (Percidæ, Cyprinidæ) far excel it in attractiveness as aquarium fishes. Unfortunately they are less hardy. Many varieties and monstrosities of the goldfish have been produced by domestication.

Fig. 133.—Lower pharyngeal of Placopharynx duquesnii (Le Sueur).

The Catostomidæ.—The suckers, or Catostomidæ, are an offshoot from the Cyprinidæ, differing chiefly in the structure of the mouth and of the lower pharyngeal bones. The border of the mouth above is formed mesially by the small premaxillaries and laterally by the maxillaries. The teeth of the lower pharyngeals are small and very numerous, arranged in one series like the teeth of a comb. The lips are usually thick and fleshy, and the dorsal fin is more or less elongate (its rays eleven to fifty in number), characters which distinguish the suckers from the American Cyprinidæ generally, but not from those of the Old World.

About sixty species of suckers are known, all of them found in the rivers of North America except two, which have been recorded on rather uncertain authority from Siberia and China. Only two or three of the species extend their range south of the Tropic of Cancer into Mexico or Central America, and none 172occur in Cuba nor in any of the neighboring islands. The majority of the genera are restricted to the region east of the Rocky Mountains, although species of Catostomus, Chasmistes, Deltistes, Xyrauchen, and Pantosteus are found in abundance in the Great Basin and the Pacific slope.

Fig. 134.—Creekfish or Chub-sucker, Erimyzon sucetta (Lacépède). Nipisink Lake, Illinois. Family Catostomidæ.

In size the suckers range from six inches in length to about three feet. As food-fishes they are held in low esteem, the flesh of all being flavorless and excessively full of small bones. Most of them are sluggish fishes; they inhabit all sorts of streams, lakes, and ponds, but even when in mountain brooks they gather in the eddies and places of greatest depth and least current. They feed on insects and small aquatic animals, and also on mud, taking in their food by suction. They are not very tenacious of life. Most of the species swarm in the spring in shallow waters. In the spawning season they migrate up smaller streams than those otherwise inhabited by them. The large species move from the large rivers into smaller ones; the small brook species go into smaller brooks. In some cases the males in spring develop black or red pigment on the body or fins, and in many cases tubercles similar to those found in the Cyprinidæ appear on the head, body, and anal and caudal fins.

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Fig. 135.—Buffalo-fish, Ictiobus cyprinella (Cuv. & Val.). Normal, Ill.

Fig. 136.—Carp-sucker, Carpiodes cyprinus (Le Sueur). Havre de Grace.

The buffalo-fishes and carp-suckers, constituting the genera Ictiobus and Carpiodes, are the largest of the Catostomidæ, and bear a considerable resemblance to the carp. They have the dorsal fin many rayed and the scales large and coarse. They abound in the large rivers and lakes between the Rocky Mountains and the Alleghanies, one species being found in Central America and a species of a closely related genus (Myxocyprinus asiaticus) being reported from eastern Asia. They rarely ascend the smaller rivers except for the purpose of spawning. Although so abundant in the Mississippi Valley as to be of importance commercially, they are very inferior as food-fishes, being coarse and bony. The genus Cycleptus contains the black-horse, or Missouri sucker, a peculiar species with a small head, elongate 174body, and jet-black coloration, which comes up the smaller rivers tributary to the Mississippi and Ohio in large numbers in the spring. Most of the other suckers belong to the genera Catostomus and Moxostoma, the latter with the large-toothed Placopharynx being known, from the red color of the fins, as red-horse, the former as sucker. Some of the species are very widely distributed, two of them (Catostomus commersoni, Erimyzon sucetta) being found in almost every stream east of the Rocky Mountains and Catostomus catostomus throughout Canada to the Arctic Sea. The most peculiar of the suckers in appearance is the harelip sucker (Quassilabia lacera) of the Western rivers. Very singular in form is the humpback or razor-back sucker of the Colorado, Xyrauchen cypho.

Fig. 137.—Common Sucker, Catostomus commersoni (Le Sueur). Ecorse, Mich.

Fig. 138.—California Sucker, Catostomus occidentalis Agassiz. (Photograph by Cloudsley Rutter.)

Fossil Cyprinidæ.—Fossil Cyprinidæ, closely related to existing forms, are found in abundance in fresh-water deposits of the Tertiary, but rarely if ever earlier than the Miocene. Cyprinus 175priscus occurs in the Miocene of Germany, perhaps showing that Germany was the original home of the so-called "German carp," afterwards actually imported to Germany from China. Some specimens referred to Barbus, Tinca, Rhodeus, Aspius, and Gobio are found in regions now inhabited by these genera, and many species are referred to the great genus Leuciscus, Leuciscus œningensis from the Miocene of Germany being perhaps the best known. Several species of Leuciscus or related genera are found in the Rocky Mountain region. Among these is the recently described Leuciscus turneri.

Fig. 139.—Pharyngeal teeth of Oregon Sucker, Catostomus macrocheilus.

Fossil Catostomidæ are very few and chiefly referred to the genus Amyzon, supposed to be allied to Erimyzon, but with a longer dorsal. Amyzon commune and other species are found in the Rocky Mountains, especially in the Miocene of the South Park in Colorado and the Eocene of Wyoming. Two or three species of Catostomus, known by their skulls, are found in the Pliocene of Idaho.

Fig. 140.—Razor-back Sucker, Xyrauchen cypho (Lockington). Green River, Utah.

The Loaches.—The Cobitidæ, or loaches, are small fishes, all less than a foot in length, inhabiting streams and ponds of Europe and Asia. In structure they are not very different from minnows, but they are rather eel-like in form, and the numerous 176long barbels about the mouth strongly suggest affinity with the catfishes. The scales are small, the pharyngeal teeth few, and the air-bladder, as in most small catfishes, enclosed in a capsule. The loaches are all bottom fishes of dark colors, tenacious of life, feeding on insects and worms. The species often bury themselves in mud and sand. They lie quiet on the bottom and move very quickly when disturbed much after the manner of darters and gobies. Species of Cobitis and Misgurnus are widely distributed from England to Japan. Nemachilus barbatulus is the commonest European species. Cobitis tænia is found, almost unchanged, from England to the streams of Japan.

Remains of fossil loaches, mostly indistinguishable from Cobitis, occur in the Miocene and more recent rocks.

From ancestors of loaches or other degraded Cyprinidæ we may trace the descent of the catfishes.

The Homalopteridæ are small loaches in the mountain streams of the East Indies. They have no air-bladder and the number of pharyngeal teeth (10 to 16) is greater than in the loaches, carp, or minnows.

The Nematognathi.—The Nematognathi (νῆμα, thread; γνάθος, jaw), known collectively as catfishes, are recognized at once by the fact that the rudimentary and usually toothless maxillary is developed as the bony base of a long barbel or feeler. Usually other feelers are found around the head, suggesting the "smellers" of a cat. The body is never scaly, being either naked and smooth or else more or less completely mailed with bony plates which often resemble superficially those of a sturgeon. Other distinctive characters are found in the skeleton, notably the absence of the subopercle, but the peculiar development of the maxillary and its barbel with the absence of scales is always distinctive. The symplectic is usually absent, and in some the air-bladder is reduced to a rudiment inclosed in a bony capsule. In almost all cases a stout spine exists in the front of the dorsal fin and in the front of each pectoral fin. This spine, made of modified or coalescent soft rays, is often a strong weapon with serrated edges and capable of inflicting a severe wound. When the fish is alarmed, it sets this spine by a rotary motion in its socket joint. It can then be depressed only by breaking it. By a rotary motion upward and toward the body the spine is again lowered. The wounds made by this spine are often painful, but this fact is due not to a specific poison but to the irregular cut and to the slime of the spine.

In two genera, Noturus and Schilbeodes, a poison-gland exists at the base of the pectoral spine, and the wound gives a sharp pain like the sting of a hornet and almost exactly like the sting of a scorpion-fish. Most of the Nematognathi possess a fleshy or adipose fin behind the dorsal, exactly as in the salmon. In 178a few cases the adipose fin develops an anterior spine and occasionally supporting rays.

All the Nematognathi are carnivorous bottom feeders, devouring any prey they can swallow. Only a few enter the sea, and they occur in the greatest abundance in the Amazon region. Upward of 1200 species, arranged in 150 genera, are recorded. They vary greatly in size, from two inches to six feet in length. All are regarded as food-fishes, but the species in the sea have very tough and flavorless flesh. Some of the others are extremely delicate, with finely flavored flesh and a grateful absence of small bones.

Families of Nematognathi.—According to Dr. Eigenmann's scheme of classification,^[11] the most primitive family of Nematognathi is that of Diplomystidæ, characterized by the presence of a well-developed maxillary, as in other soft-rayed fishes. The single species, Diplomystes papillosus, is found in the waters of Chile.

Similar to the Diplomystidæ in all other respects is the great central family of Siluridæ, by far the most numerous and important of all the divisions of Nematognathi.

The Siluridæ.—This group has the skin naked or imperfectly mailed, the barbels on the head well developed, the dorsal short, inserted forward, the adipose fin without spine, and the lower pharyngeals separate. All the marine catfishes and most of the fresh-water species belong to this group, and its members, some 700 species, abound in all parts of the world where catfishes are known—"a bloodthirsty and bullying race of rangers inhabiting the river bottoms with ever a lance at rest and ready to do battle with their nearest neighbor."

The Sea Catfish.—In the tropical seas are numerous species of catfishes belonging to Tachysurus, Arius, Galeichthys, Felichthys, and other related genera. These are sleek, silvery fishes covered with smooth skin, the head usually with a coat of mail, pierced by a central fontanelle. Some of them reach a considerable size, swarming in sandy bays. None are valued as food, being always tough and coarsely flavored. Sea birds, as the pelican, which devour these catfishes are often destroyed by 179the sudden erection of the pectoral spines. None of these are found in Europe or in Japan. Of the very many American species the gaff-topsail catfish (Felichthys felis), noted for its very high spines, extends farthest north and is one of the very largest species. This genus has two barbels at the chin. Most others have four. The commonest sea catfish of the Carolina coast is Galeichthys milberti. In Tachysurus the teeth on the palate are rounded, in most of the others they are in villiform bands.

Fig. 141.—Gaff-topsail Cat, Felichthys felis (L.). Wood's Hole.

Fig. 142.—Sea Catfish, Galeichthys milberti (Cuv. & Val.). Pensacola.

In most or all of the sea catfish the eggs, as large as small peas, are taken into the mouth of the male and there cared for until hatched.

The Channel Cats.—In all the rivers of North America east of the Rocky Mountains are found catfishes in great variety. The channel cats, Ictalurus, known most readily by the forked tails, are the largest in size and most valued as food. The technical 180character of the genus is the backward continuation of the supraoccipital, forming a bony bridge to the base of the dorsal. The great blue cat, Ictalurus furcatus, abounds throughout the large rivers of the Southern States and reaches a weight of 150 pounds or more. It is an excellent food and its firm flesh is readily cut into steaks. In the Great Lakes and northward is a very similar species, also of large size, which has been called Ictalurus lacustris. Another similar species is the willow cat, Ictalurus anguilla. The white channel-cat, Ictalurus punctatus, reaches a much smaller size and abounds on the ripples in clear swift streams of the Southwest, such as the Cumberland, the Alabama, and the Gasconade. It is a very delicate food-fish, with tender white flesh of excellent flavor.

Fig. 143.—Channel Catfish, Ictalurus punctatus (Rafinesque). Illinois River. Family Siluridæ.

Horned Pout.—The genus Ameiurus includes the smaller brown catfish, horned pout, or bullhead. The body is more plump and the caudal fin is usually but not always rounded. The many species are widely diffused, abounding in brooks, lakes, and ponds. Ameiurus nebulosus is the best-known species, ranging from New England to Texas, known in the East as horned pout. It has been successfully introduced into the Sacramento, where it abounds, as well as its congener, Ameiurus catus (see Fig. 229, Vol. I), the white bullhead, brought with it from the Potomac. The latter species has a broader head and concave or notched tail. All the species are good food-fishes. All are extremely tenacious of life, and all are alike valued by the urchin, for they will bite vigorously at any sort of bait. All must be handled with care, for the sharp pectoral spines make an ugly cut, a species of 181wound from which few boys' hands in the catfish region are often free.

Fig. 144.—Horned pout, Ameiurus nebulosus (Le Sueur). (From life by Dr. R. W. Shufeldt.)

In the caves about Conestoga River in Lancaster County, Pennsylvania, is a partly blind catfish, evidently derived from local species outside the cave. It has been named Gronias nigrilabris.

A few species are found in Mexico, one of them, Ictalurus 182meridionalis, as far south as Rio Usamacinta on the boundary of Guatemala.

Besides these, a large channel-cat of peculiar dentition, known as Istlarius balsanus, abounds in the basin of Rio Balsas. In Mexico all catfishes are known as Bagre, this species as Bagre de Rio.

The genus Leptops includes the great yellow catfish, or goujon, known at once by the projecting lower jaw. It is a mottled olive and yellow fish of repulsive exterior, and it reaches a very great size. It is, however, a good food-fish.

The Mad-toms.—The genera Noturus and Schilbeodes are composed of diminutive catfishes, having the pectoral spine armed at base, with a poison sac which renders its sting extremely painful though not dangerous. The numerous species of this genus, known as "mad-toms" and "stone cats," live among weeds in brooks and sluggish streams. Most of them rarely exceed three inches in length, and their varied colors make them attractive in the aquarium.

Fig. 145.—Mad-tom, Schilbeodes furiosus Jordan & Meek. Showing the poisoned pectoral spine. Family Siluridæ. Neuse River.

The Old World Catfishes.—In the catfishes of the Old World and their relatives, the adipose fin is rudimentary or wanting. The chief species found in Europe is the huge sheatfish, or wels, Silurus glanis. This, next to the sturgeon, is the largest river fish in Europe, weighing 300 to 400 pounds. It is not found in England, France, or Italy, but abounds in the Danube. It is a lazy fish, hiding in the mud and thus escaping from nets. It is very voracious, and many stories are told of the contents of its stomach. A small child swallowed whole is recorded from Thorn, and there are still more remarkable stories, but not 183properly vouched for. The sheatfish is brown in color, naked, sleek, and much like an American Ameiurus save that its tail is much longer and more eel-like. Another large catfish, known to the ancients, but only recently rediscovered by Agassiz and Garman, is Parasilurus aristotelis of the rivers of Greece. In China and Japan is the very similar Namazu, or Japanese catfish, Parasilurus asotus, often found in ponds and used as food. Numerous smaller related catfishes, Porcus (Bagrus), Pseudobagrus, and related genera swarm in the brooks and ponds of the Orient.

Fig. 146.—Electric Catfish, Torpedo electricus (Gmelin). Congo River. (After Boulenger.)

In the genus Torpedo (Malapterurus) the dorsal fin is wanting. Torpedo electricus, the electric catfish of the Nile, is a species of much interest to anatomists. The shock is like that of a Leyden jar. The structures concerned are noticed on p. 186, Vol. I. The generic name Torpedo was applied to the electric catfish before its use for the electric ray.

In South America a multitude of genera and species cluster around the genus Pimelodus. Some of them have the snout very long and spatulate. Most of them possess a very long adipose fin. The species are generally small in size and with smooth skin like the North American catfishes. Still other species in great numbers are grouped around the genus Doras. In this group the snout projects, bearing the small mouth at its end, and the lateral line is armed behind with spinous shields. All but one of the genera belong to the Amazon district, Synodontis being found in Africa.

Concerning Doras, Dr. Günther observes: "These fishes have excited attention by their habit of traveling during the dry season from a piece of water about to dry up in quest of a pond of greater capacity. These journeys are occasionally of such a length that the fish spends whole nights on the way, 184and the bands of scaly travelers are sometimes so large that the Indians who happen to meet them fill many baskets of the prey thus placed in their hands. The Indians suppose that the fish carry a supply of water with them, but they have no special organs and can only do so by closing the gill-openings or by retaining a little water between the plates of their bodies, as Hancock supposes. The same naturalist adds that they make regular nests, in which they cover up their eggs with care and defend them, male and female uniting in this parental duty until the eggs are hatched. The nest is constructed, at the beginning of the rainy season, of leaves and is sometimes placed in a hole scooped out of the beach."

The Sisoridæ.—The Sisoridæ are small catfishes found in swift mountain streams of northern India. In some of the genera (Pseudecheneis) in swift streams a sucking-disk formed of longitudinal plates of skin is formed on the breast. This enables these fishes to resist the force of the water. In one genus, Exostoma, plates of skin about the mouth serve the same purpose.

The Bunocephalidæ are South American catfishes with the dorsal fin undeveloped and the top of the head rough. In Platystacus (Aspredo), the eggs are carried on the belly of the female, which is provided with spongy tentacles to which the eggs are attached. After the breeding season the ventral surface becomes again smooth.

The Plotosidæ.—The Plotosidæ are naked catfishes, largely marine, found along the coasts of Asia. In these fishes the second dorsal is very long. Plotosus anguillaris, the sea catfish of Japan, is a small species striped with yellow and armed with sharp pectoral spines which render it a very disagreeable object to the fishermen. In sandy bays like that of Nagasaki it is very abundant. Allied to this is the small Asiatic family of Chacidæ.

The Chlariidæ.—The Chlariidæ are eel-like, with a soft skeleton and a peculiar accessory gill. These abound in the swamps and muddy streams of India, where some species reach a length of six feet. One species, Chlarias magur, has been brought by the Chinese to Hawaii, where it flourishes in the same 185waters as Ameiurus nebulosus, brought from the Potomac and by Chinese carried from San Francisco.

The Hypophthalmidæ and Pygidiidæ.—The Hypophthalmidæ have the minute air-bladder inclosed in a long bony capsule. The eyes are placed very low and the skin is smooth. The statement that this family lacks the auditory apparatus is not correct. The few species belong to northern South America.

Fig. 147.—An African Catfish, Chlarias breviceps Boulenger. Congo River. Family Chlariidæ. (After Boulenger.)

Allied to this group is the family Pygidiidæ with a differently formed bony capsule and no adipose fin. The numerous species are all South American, mostly of mountain streams of high altitude. Some are very small. Certain species are said to flee for protection into the gill-cavity of larger catfishes. Some are reported to enter the urethra of bathers, causing severe injuries. The resemblance of certain species to the loaches, or Cobitidæ, is very striking. This similarity is due to the results of similar environment and necessarily parallel habits. The Argidæ have the capsule of the air-bladder formed in a still different fashion. The few species are very small, inhabitants of the streams of the high Andes.

The Loricariidæ.—In the family of Loricariidæ the sides and back are armed with rough bony plates. The small air-bladder is still in a bony capsule, and the mouth is small with thick fringed lips. The numerous species are all small fishes of the South American waters, bearing a strong external resemblance to Agonidæ, but wholly different in anatomy.

The Callichthyidæ.—The Callichthyidæ are also small fishes armed with a bony interlocking coat of mail. They are closely allied to the Pygidiidæ. The body is more robust than in the Callichthyidæ and the coat of mail is differently formed. The species swarm in the rivers of northern South America, where 186with the mailed Loricariidæ they form a conspicuous part of the fish fauna.

Fig. 148.—Loricaria aurea Steindachner, a mailed Catfish from Rio Meta, Venezuela. Family Loricariidæ. (After Steindachner.)

Fossil Catfishes.—Fossil catfishes are very few in number. Siluridæ, allied to Chlarias, Bagarius, Heterobranchus, and other fresh-water forms of India, are found in the late Tertiary rocks of Sumatra, and catfish spines exist in the Tertiary rocks of the United States. Vertebræ in the Canadian Oligocene have been referred by Cope to species of Ameiurus (A. cancellatus and A. maconnelli). Rhineastes peltatus and six other species, perhaps allied to Pimelodus, have been described by Cope from Eocene of Wyoming and Colorado. Bucklandium diluvii is found in the Eocene London clays, and several species apparently marine, referred to the neighborhood of Tachysurus or Arius, are found in Eocene rocks of England.

There is no evidence that the group of catfishes has any great antiquity, or that its members were ever so numerous and varied as at the present time. The group is evidently derived from scaly ancestors, and its peculiarities are due to specialization of certain parts and degeneration of others.

There is not the slightest reason for regarding the catfishes as direct descendants of the sturgeon or other Ganoid type. They should rather be looked upon as a degenerate and highly modified offshoot from the primitive Characins.

187Order Gymnonoti.—At the end of the series of Ostariophysans we may place the Gymnonoti (γυμνός, bare; νῶτος, back). This group contains about thirty species of fishes from the rivers of South America and Central America. All are eel-like in form, though the skeleton with the shoulder-girdle suspended from the cranium is quite unlike that of a true eel. There is no dorsal fin. The vent is at the throat and the anal is excessively long. The gill-opening is small as in the eel, and as in most elongate fishes, the ventral fins are undeveloped. The body is naked or covered with small scales.

Two families are recognized, differing widely in appearance. The Electrophoridæ constitutes by itself Cope's order of Glanencheli (γλανίς, catfish; ἔγχελυς, eel). This group he regards as intermediate between the eel-like catfishes (Chlarias) and the true eels. It is naked and eel-shaped, with a short head and projecting lower jaw like that of the true eel. The single species, Electrophorus electricus, inhabits the rivers of Brazil, reaching a length of six feet, and is the most powerful of all electric fishes. Its electric organs on the tail are derived from modified muscular tissue. They are described on p. 170, Vol. I.

The Gymnotidæ are much smaller in size, with compressed scaly bodies and the mouth at the end of a long snout. The numerous species are all fishes without electric organs. Eigenmannia humboldti of the Panama region is a characteristic species. No fossil Gymnonoti are recorded.

Order Scyphophori.—The Scyphophori (σκύφος, cup; φορέω, to bear) constitutes a small order which lies apparently between the Gymnonoti and the Isospondyli. Boulenger unites it with the Isospondyli. The species, about seventy-five in number, inhabit the rivers of Africa, where they are important as food-fishes. In all there is a deep cavity on each side of the cranium covered by a thin bony plate, the supertemporal bone. There is no symplectic bone, and the subopercle is very small or concealed. The gill-openings are narrow and there are no pharyngeal teeth. The air-bladder connects with the ear, but not apparently in the same way as with the Ostariophysan fishes, to which, however, the Scyphophori are most nearly related. In all the Scyphophori the body is oblong, covered with cycloid scales, the head is naked, there are no barbels, and the small mouth is at the end of a long snout. All the species possess a peculiar organ on the tail, which with reference to a similar structure in Torpedo and Electrophorus is held to be a degenerate electric organ. According to Günther, "it is without electric functions, but evidently representing a transitional condition from muscular substance to an electric organ. It is an oblong capsule divided into numerous compartments by vertical transverse septa and containing a gelatinous substance."

The Mormyridæ.—There are two families of Scyphophori. The Mormyridæ have the ordinary fins and tail of fishes and the Gymnarchidæ are eel-like, with ventrals, anal and caudal wanting. Gymnarchus miloticus of the Nile reaches a length of six feet, and it is remarkable as retaining the cellular structure of the air-bladder as seen in the garpike and bowfin. It doubtless serves as an imperfect lung.

189The best-known genus of Scyphophori is Mormyrus. Species of this genus found in the Nile were worshiped as sacred by the ancient Egyptians and pictures of Mormyrus are often seen among the emblematic inscriptions. The Egyptians did not eat the Mormyrus because with two other fishes it was accused of having devoured a limb from the body of Osiris, so that Isis was unable to recover it when she gathered the scattered remains of her husband.

In Mormyrus the bones of the head are covered by skin, the snout is more or less elongated, and the tail is generally short and insignificant. One of the most characteristically eccentric species is Gnathonemus curvirostris, lately discovered by Dr. Boulenger from the Congo. Fossil Mormyridæ are unknown.

Fig. 149.—Gnathonemus curvirostris Boulenger. Family Mormyridæ. Congo River. (After Boulenger.)

The Haplomi.—In the groups called Iniomi and Lyopomi, the mesocoracoid arch is imperfect or wanting, a condition which in some cases may be due to the degeneration produced by deep-sea life. In the eels a similar condition obtains. In the group called Haplomi (ἁπλοός, simple; ὤμος, shoulder), as in all the groups of fishes yet to be discussed, this arch is wholly wanting at all stages of development. In common with the Isospondyli and with soft-rayed fishes in general the air-bladder has a persistent air-duct, all the fins are without true spines, the ventral fins are abdominal, and the scales are cycloid. The group is a transitional one, lying almost equidistant between the Isospondyli and the Acanthopterygii. Gill unites it with the latter and Woodward with the former. We may regard it for the present 190as a distinct order, although no character of high importance separates it from either. Hay unites the Haplomi with the Synentognathi to form the order of Mesichthyes, or transitional fishes, but the affinities of either with other groups are quite as well marked as their relation to each other. Boulenger unites the Iniomi with the Haplomi, an arrangement which apparently has merit, for the most primitive and non-degenerate Iniomi, as Aulopus and Synodus, lack both mesocoracoid and orbitosphenoid. These bones are characteristic of the Isospondyli, but are wanting in Haplomi.

There is no adipose dorsal in the typical Haplomi, the dorsal is inserted far back, and the head is generally scaly. Most but not all of the species are of small size, living in fresh or brackish water, and they are found in almost all warm regions, though scantily represented in California, Japan, and Polynesia. The four families of typical Haplomi differ considerably from one another and are easily distinguished, although obviously related. Several other families are provisionally added to this group on account of agreement in technical characters, but their actual relationships are uncertain.

The Pikes.—The Esocidæ have the body long and slender and the mouth large, its bones armed with very strong, sharp teeth of different sizes, some of them being movable. The upper jaw is not projectile, and its margin, as in the Salmonidæ, is formed by the maxillary. The scales are small, and the dorsal fin far back and opposite the anal, and the stomach is without pyloric cæca. There is but a single genus, Esox (Lucius of Rafinesque), with about five or six living species. Four of these are North American, the other one being found in Europe, Asia, and North America.

All the pikes are greedy and voracious fishes, very destructive to other species which may happen to be their neighbors; "mere machines for the assimilation of other organisms." Thoreau describes the pike as "the swiftest, wariest, and most ravenous of fishes, which Josselyn calls the river-wolf. It is a solemn, stately, ruminant fish, lurking under the shadow of a lily-pad at noon, with still, circumspect, voracious eye; motionless as a jewel set in water, or moving slowly along to take up its position; darting from time to time at such unlucky fish or frog or insect as comes within its range, and swallowing it at one gulp. Sometimes a striped snake, bound for greener meadows across the stream, ends its undulatory progress in the same receptacle."

191

Fig. 150.—The Pike, Esox-lucius L. (From life by R. W. Shufeldt.)

192As food-fishes, all the Esocidæ rank high. Their flesh is white, fine-grained, disposed in flakes, and of excellent flavor.

The finest of the Esocidæ, a species to be compared, as a grand game fish, with the salmon, is the muskallunge (Esox masquinongy). Technically this species may be known by the fact that its cheeks and opercles are both naked on the lower half. It may be known also by its great size and by its color, young and old being spotted with black on a golden-olive ground.

Fig. 151.—Muskallunge, Esox masquinongy Mitchill. Ecorse, Mich.

The muskallunge is found only in the Great Lake region, where it inhabits the deeper waters, except for a short time in the spring, when it enters the streams to spawn. It often reaches a length of six feet and a weight of sixty to eighty pounds. It is necessarily somewhat rare, for no small locality would furnish food for more than one such giant. It is, says Hallock, "a long, slim, strong, and swift fish, in every way formed for the life it leads, that of a dauntless marauder."

A second species of muskallunge, Esox ohiensis, unspotted but vaguely cross-barred, occurs sparingly in the Ohio River and the upper Mississippi Valley. It is especially abundant in Chautauqua Lake.

The pike (Esox lucius) is smaller than the muskallunge, and is technically best distinguished by the fact that the opercles are naked below, while the cheeks are entirely scaly. The spots and cross-bars in the pike are whitish or yellowish, and always paler than the olive-gray ground color. It is the most 193widely distributed of all fresh-water fishes, being found from the upper Mississippi Valley, the Great Lakes, and New England to Alaska and throughout northern Asia and Europe. It reaches a weight of ten to twenty pounds or more, being a large strong fish in its way, inferior only to the muskallunge. In England Esox lucius is known as the pike, while its young are called by the diminutive term pickerel. In America the name pickerel is usually given to the smaller species, and sometimes even to Esox lucius itself, the word being with us a synonym for pike, not a diminutive.

Of the small pike or pickerel we have three species in the eastern United States. They are greenish in color and banded or reticulated, rather than spotted, and, in all, the opercles as well as the cheeks are fully covered with scales. One of these (Esox reticulatus) is the common pickerel of the Eastern States, which reaches a respectable size and is excellent as food. The others, Esox americanus along the Atlantic seaboard and Esox vermiculatus in the middle West, seldom exceed a foot in length and are of no economic importance.

Numerous fossil species are found in the Tertiary of Europe, Esox lepidotus from the Miocene of Baden being one of the earliest and the best known; in this species the scales are much larger than in the recent species. The fossil remains would seem to indicate that the origin of the family was in southern Europe, although most of the living species are American.

Fig. 152.—Mud-minnow, Umbra pygmæa (De Kay). New Jersey.

The Mud-minnows.—Close to the pike is the family of Umbridæ, or mud-minnows, which technically differ from the pikes only in the short snout, small mouth, and weak dentition. The 194mud-minnows are small, sluggish, carnivorous fishes living in the mud at the bottom of cold, clear streams and ponds. They are extremely tenacious of life, though soon suffocated in warm waters. The barred mud-minnow of the prairies of the middle West (Umbra limi) often remains in dried sloughs and bog-holes, and has been sometimes plowed up alive. Umbra pygmæa, a striped species, is found in the Eastern States and Umbra crameri in bogs and brooks along the Danube. This wide break in distribution seems to indicate a former wide extension of the range of Umbridæ, perhaps coextensive with Esox. Fossil Umbridæ are, however, not yet recognized.

The Killifishes.—Most of the recent Haplomi belong to the family of Pœciliidæ (killifishes, or Cyprinodonts). In this group the small mouth is extremely protractile, its margin formed by the premaxillaries alone much as in the spiny-rayed fishes. The teeth are small and of various forms according to the food. In most of the herbivorous forms they are incisor-like, serrate, and loosely inserted in the lips. In the species that eat insects or worms they are more firmly fixed. The head is scaly, the stomach without cæca, and the intestines are long in the plant-eating species and short in the others. There are nearly 200 species, very abundant from New England and California southward to Argentina, and in Asia and Africa also. In regions where rice is produced, they swarm in the rice swamps and ditches. Some of them enter the sea, but none of them go far from shore. Some are brilliantly colored, and in many species the males are quite unlike the females, being smaller and more showy. The largest species (Fundulus, Anableps) rarely reach the length of a foot, while Heterandria formosa, a diminutive inhabitant of the Florida rivers, scarcely reaches an inch. Some species are oviparous, but in most of the herbivorous forms, and some of the others, the eggs are hatched within the body, and the anal in the male is modified into a long sword-shaped intromittent organ, placed farther forward than the anal in the female. The young when born closely resemble the parent. Most of the insectivorous species swim at the surface, moving slowly with the eyes partly out of water. This habit in the genus Anableps (four-eyed fish, or Cuatro ojos) is associated with an 195extraordinary structure of the eye. This organ is prominent and is divided by a horizontal partition into two parts, the upper, less convex, adopted for sight in the air, the lower in the water. The few species of Anableps are found in tropical America. The species of some genera swim near the bottom, but always in very shallow waters. All are very tenacious of life, and none have any commercial value although the flesh is good.

Fig. 152a.—Four-eyed Fish, Anableps dovii Gill. Tehuantepec, Mexico.

The unique structure of the eye of this curious fish has been carefully studied by Mr. M. C. Marsh, pathologist of the U. S. Fish Commission, who furnishes the following notes published by Evermann & Goldsborough:

"The eye is crossed by a bar, like the diameter of a circle, and parallel with the length of the body. This bar is darker than the other external portions of the eyeball and has its edges darker still. Dividing the external aspect of the eye equally, it has its lower edge on the same level as the back of the fish, which is flat and straight from snout to dorsal, or nearly the whole length of the fish; so that when the body of the fish is just submerged the level of the water reaches to this bar, and the lower half of the eye is in water, the upper half in the air. Upon dissecting the eyeball from the orbit, it appears nearly round. A membranous sheath covers the external part and invests most of the ball. It may be peeled off, when the dark bar on the external portion of the eye is seen to be upon this membrane, which may correspond to the conjunctiva. The back portion of the eyeball being cut off, one lens is found. The lining of the ball consists, in front, of one black layer, evidently choroid. Behind there is a retinal layer. The choroid layer turns up anteriorly, making a free edge comparable to an iris. The free edge is chiefly evident in the lower part of the eye. A large pupil is left, but is divided by two flaps, continuations of the choroid coat, projecting from either side and overlapping. 196There are properly then two pupils, an upper and lower, separated by a band consisting of the two flaps, which may probably, by moving upward and downward, increase or diminish the size of either pupil; an upward motion of the flaps increasing the lower pupil at the expense of the other, and vice versa."

This division of the pupil into two parts permits the fish, when swimming at the surface of the water, as is its usual custom, to see in the air with the upper portion and in the water with the lower. It is thus able to see not only such insects as are upon the surface of the water or flying in the air above, but also any that may be swimming beneath the surface.

Fig. 153.—Round Minnow, Cyprinodon variegatus Lacépède. St. George Island, Maryland.

According to Mr. E. W. Nelson, "the individuals of this species swim always at the surface and in little schools arranged in platoons or abreast. They always swim headed upstream against the current, and feed upon floating matter which the current brings them. A platoon may be seen in regular formation breasting the current, either making slight headway upstream or merely maintaining their station, and on the qui vive for any suitable food the current may bring. Now and then one may be seen to dart forward, seize a floating food particle, and then resume its place in the platoon. And thus 197they may be observed feeding for long periods. They are almost invariably found in running water well out in the stream, or at least where the current is strongest and where floating matter is most abundant, for it is upon floating matter that they seem chiefly to depend. They are not known to jump out of the water to catch insects flying in the air or resting upon vegetation above the water surface, nor do they seem to feed to any extent upon all small crustaceans or other portions of the plankton beneath the surface.

Fig. 154.—Everglade Minnow, Jordanella floridæ Goode & Bean. Everglades of Florida.

"When alarmed—and they are wary and very easily frightened—they escape by skipping or jumping over the water, 2 or 3 feet at a skip. They rise entirely out of the water, and at a considerable angle, the head pointing upward. In descending the tail strikes the water first and apparently by a sculling motion new impetus is acquired for another leap. This skipping may continue until the school is widely scattered. When a school has become scattered, and after the cause of their fright has disappeared, the individuals soon rejoin each other. First two will join each other and one by one the others will join them until the whole school is together again. Rarely do they attempt to dive or get beneath the surface; when they do they have great difficulty in keeping under and soon come to the surface again."

198

Fig. 155.—Mayfish, Fundulus majalis (L.) (male). Wood's Hole.

Fig. 156.—Mayfish, Fundulus majalis (female). Wood's Hole.

Fig. 157.—Top-minnow, Zygonectes notatus (Rafinesque). Eureka Springs, Ark.

199

Fig. 158.—Death Valley Fish, Empetrichthys merriami Gilbert. Amargosa Desert, Cal. Family Pœciliidæ. (After Gilbert.)

Fig. 159.—Sword-tail Minnow, male, Xiphophorus helleri Heckel. The anal fin modified as an intromittent organ. Vera Cruz.

Of the many genera of Pœciliidæ, top-minnows, and killifishes we may mention the following: Cyprinodon is made up of chubby little fishes of eastern America with tricuspid, incisor teeth, oviparous and omnivorous. Very similar to these but smaller are the species of Lebias in southern Europe. Jordanella floridæ of the Florida everglades is similar, but with the dorsal fin long and its first ray enlarged and spine-like. It strongly resembles a young sunfish. Most of the larger forms belong to Fundulus, a genus widely distributed from Maine to Guatemala and north to Kansas and southern California. Fundulus majalis, the Mayfish of the Atlantic Coast, is the largest of the genus. Fundulus heteroclitus, the killifish, the most abundant. Fundulus diaphanus inhabits sea and lake indiscriminately. Fundulus stellifer of the Alabama is beautifully colored, as is Fundulus zebrinus of the Rio Grande. The genus Zygonectes includes dwarf species similar to Fundulus, and Adinia includes those with short, deep body. Goodea atripinnis with tricuspid teeth lives in warm springs in Mexico, and several species of Goodea, Gambusia, Pœcilia, and other genera inhabit hot springs of Mexico, Central America, and Africa. The genus Gambusia, the top-minnows, includes numerous species with dwarf males having the anal modified. Gambusia affinis abounds in all kinds of sluggish water in the southern lowlands, gutters and even sewers included. It brings forth its brood in early spring. Viviparous and herbivorous with modified anal fin are the species of Pœcilia, abundant throughout Mexico and southward to Brazil; Mollienesia very similar, with a banner-like dorsal fin, showily marked, occurs from Louisiana southward, and Xiphophorus, with a sword-shaped lobe on the caudal, abounds in Mexico; Characodon and Goodea (see Fig. 53, Vol. I) in Mexico have notched teeth, and finally, Heterandria contains some of the least of fishes, the handsomely colored males barely half an inch long.

200

Fig. 160.—Goodea luitpoldi (Steindachner). A viviparous fish from Lake Patzcuaro, Mexico. Family Pœciliidæ. (After Meek.)

201In Lake Titicaca in the high Andes is a peculiar genus (Orestias) without ventral fins. Still more peculiar is Empetrichthys merriami of the desert springs of the hot and rainless Death Valley in California, similar to Orestias, but with enormously enlarged pharyngeals and pharyngeal teeth, an adaptation to some unknown purpose. Fossil Cyprinodonts are not rare from the Miocene in southern Europe. The numerous species are allied to Lebias and Cyprinodon, and are referred to Prolebias and Pachylebias. None are American, although two American extinct genera, Gephyrura and Proballostomus, are probably allied to this group.

Amblyopsidæ.—The cavefishes, Amblyopsidæ, are the most remarkable of the haplomous fishes. In this family the vent is placed at the throat. The form is that of the Pœciliidæ, but the mouth is larger and not protractile. The species are viviparous, the young being born at about the length of a quarter of an inch.

Fig. 161.—Dismal Swamp Fish, Chologaster cornutus Agassiz. Supposed ancestor of Typhlichthys. Virginia.

In the primitive genus Chologaster, the fish of the Dismal Swamp, the eyes are small but normally developed. Chologaster cornutus abounds in the black waters of the Dismal Swamp 202of Virginia, thence southward through swamps and rice-fields to Okefinokee Swamp in northern Florida. It is a small fish, less than two inches long, striped with black, and with the habit of a top-minnow. Other species of Chologaster, possessing eyes and color, but provided also with tactile papillæ, are found in cave springs in Tennessee and southern Illinois.

Fig. 162.—Blind Cave-fish, Typhlichthys subterraneus Girard. Mammoth Cave, Kentucky.

From Chologaster is directly descended the small blindfish Typhlichthys subterraneus of the caves of the Subcarboniferous limestone rocks of southern Indiana and southward to northern Alabama. As in Chologaster, the ventral fins are wanting. The eyes, present in the young, become defective and useless in the adult, when they are almost hidden by other tissues. The different parts of the eye are all more or less incomplete, being without function. The structure of the eye has been described in much detail in several papers by Dr. Carl H. Eigenmann. As to the cause of the loss of eyesight two chief theories exist—the Lamarckian theory of the inheritance in the species of the results of disuse in the individual and the Weissmannian doctrine that the loss of sight is a result of panmixia or cessation of selection. This may be extended to cover reversal of selection, as in the depths of the great caves the fish without eyes would be at some slight advantage. Dr. Eigenmann inclines to the Lamarckian doctrine, but the evidence brought forward fails to convince the present writer that results of individual use or disuse ever become hereditary or that they are ever incorporated in the characters of a species. In the caves of southern Missouri is an independent case of similar degradation. Troglichthys rosæ, the blindfish of this region, has the eye in a different phase of degeneration. It is thought to be separately descended from 203some other species of Chologaster. Of this species Mr. Garman and Mr. Eigenmann have given detailed accounts from somewhat different points of view.

Concerning the habits of the blindfish (Troglichthys rosæ), Mr. Garman quotes the following from notes of Miss Ruth Hoppin, of Jasper County, Missouri: "For about two weeks I have been watching a fish taken from a well. I gave him considerable water, changed once a day, and kept him in an uninhabited place subject to as few changes of temperature as possible. He seems perfectly healthy and as lively as when first taken from the well. If not capable of long fasts, he must live on small organisms my eye cannot discern. He is hardly ever still, but moves about the sides of the vessel constantly, down and up, as if needing the air. He never swims through the body of the water away from the sides unless disturbed. Passing the finger over the sides of the vessel under water I find it slippery. I am careful not to disturb this slimy coating when the water is changed.... Numerous tests convince me that it is through the sense of touch, and not through hearing, that the fish is disturbed; I may scream or strike metal bodies together over him as near as possible, yet he seems to take no notice whatever. If I strike the vessel so that the water is set in motion, he darts away from that side through the mass of water, instead of around in his usual way. If I stir the water or touch the fish, no matter how lightly, his actions are the same."

Fig. 163.—Blindfish of the Mammoth Cave, Amblyopsis spelæus (De Kay). Mammoth Cave, Kentucky.

The more famous blindfish of the Mammoth Cave, Amblyopsis spelæus, reaches a length of five inches. It possesses ventral fins. From this fact we may infer its descent from 204some extinct genus which, unlike Chologaster, retains these fins. The translucent body, as in the other blindfishes, is covered with very delicate tactile papillæ, which form a very delicate organ of touch.

The anomalous position of the vent in Amblyopsidæ occurs again in an equally singular fish, Aphredoderus sayanus, which is found in the same waters throughout the same region in which Chologaster occurs. It would seem as if these lowland fishes of the southern swamps were remains of a once much more extensive fauna.

No fossil allies of Chologaster are known.

Kneriidæ, etc.—The members of the order of Haplomi, recorded above, differ widely among themselves in various details of osteology. There are other families, probably belonging here, which are still more aberrant. Among these are the Kneriidæ, and perhaps the entire series of forms called Iniomi, most of which possess the osteological traits of the Haplomi.

The family of Kneriidæ includes a few very small fishes of the rivers of Africa.

The Galaxiidæ.—The Galaxiidæ are trout-like fishes of the southern rivers, where they take the place of the trout of the northern zones. The species lack the adipose fins and have the dorsal inserted well backward. According to Boulenger these fishes, having no mesocoraoid, should be placed among the Haplomi. Yet their relation to the Haplochitonidæ is very close and both families may really belong to the Isospondyli. Galaxias truttaceus is the kokopu, or "trout," of New Zealand. Galaxias ocellatus is the yarra trout of Australia. Several other species are found in southern Australia, Tasmania, Patagonia, and the Falkland Islands, and even in South Africa. This very wide distribution in the rivers remote from each other has given rise to the suggestion of a former land connection between Australia and Patagonia. Other similar facts have led some geologists to believe in the existence of a former great continent called Antarctica, now submerged except that part which constitutes the present unknown land of the Antarctic.

As intimated on p. 253, Vol. I, this distribution of Galaxias with similar anomalies in other groups could not if unsupported by geological evidence be held to prove the former extension 205of the Antarctic continent. Dr. Boulenger^[12] has recently shown that Galaxias lives freely in salt water, a fact sufficient 206to account for its wide distribution in the rivers of the southern hemisphere.

Neochanna is an ally of Galaxias living in burrows in the clay or mud like a crayfish, often at a distance from water. As in various other mud-living types, the ventral fins are obsolete.

Order Xenomi.—We must place near the Haplomi the singular group of Xenomi (ξενός, strange; ὤμος, shoulder), regarded by Dr. Gill as a distinct order. Externally these fish much resemble the mud-minnows, differing mainly in the very broad pectorals. But the skeleton is thin and papery, the two coracoids forming a single cartilaginous plate imperfectly divided. The pectorals are attached directly to this without the intervention of actinosts, but in the distal third, according to Dr. Charles H. Gilbert, the coracoid plate begins to break up into a fringe of narrow cartilaginous strips. These about equal the very large number (33 to 36) of pectoral rays, the basal part of each ray being slightly forked to receive the tip of the cartilaginous strip.

Fig. 164.—Alaska Blackfish, Dallia pectoralis (Bean). St. Michaels, Alaska.

"In the deep-sea eels of the order Heteromi there is a somewhat similar condition of the coracoid elements inasmuch as the hypercoracoid and hypocoracoid though present are merely membranous elements surrounded by cartilage and the actinosts are greatly reduced. It seems probable that we are dealing in the two cases with independent degeneration of the shoulder-girdle and that the two groups (Xenomi and Heteromi) are not really related." (Gilbert.)

Of the single family Dalliidæ, one species is known, the Alaska blackfish, Dallia pectoralis.

207This animal, formed like a mud-minnow, reaches a length of eight inches and swarms in the bogs and sphagnum swamps of northwestern Alaska and westward through Siberia. It is found in countless numbers according to its discoverer, Mr. L. M. Turner, "wherever there is water enough to wet the skin of a fish," and wherever it occurs it forms the chief food of the natives. Its vitality is most extraordinary. Blackfishes will remain frozen in baskets for weeks and when thawed out are as lively as ever. Turner gives an account of a frozen individual swallowed by a dog which escaped in safety after being thawed out by the heat of the dog's stomach.

Order Acanthopterygii, the Spiny-rayed Fishes.—The most of the remaining bony fishes constitute a natural group for which the name Acanthopterygii (ἄκανθα, spine; πτερύξ, πτερόν, fin or wing) may be used. This name is often written Actinopteri, a form equally correct and more euphonious and convenient. These fishes are characterized, with numerous exceptions, by the presence of fin spines, by the connection of the ventral fins with the shoulder-girdle, by the presence in general of more than one spine in the anterior part of dorsal and anal fins, and as a rule of one spine and five rays in the ventral fins, and by the absence in the adult of a duct to the air-bladder. Minor characters are these: the pectoral fins are inserted high on the shoulder-girdle, the scales are often ctenoid, and the edge of the upper jaw is formed by the premaxillary alone, the maxillary being always toothless.

But it is impossible to define or limit the group by any single character or group of characters. It is connected with the Malacopterygii through the Haplomi on the one hand by transitional groups of genera which may lack any one of these characters. On the other hand, in the extreme forms, each of these distinctive characters may be lost through degeneration. Thus fin spines, ctenoid scales, and the homocercal tail are lost in the codfishes, the connection of ventrals with shoulder-girdle fails in the Percesoces, etc., and the development of the air-duct is subject to all sorts of variations. In one family even the adipose fin remains through all the changes and modifications the species have undergone.

The various transitional forms between the Haplomi and the perch-like fishes have been from time to time regarded as 209separate orders. Some of them are more related to the perch, others rather to ancestors of salmon or pike, while still others are degenerate offshoots, far enough from either.

On the whole, all these forms, medium, extreme and transitional, may well be placed in one order, which would include the primitive flying-fishes and mullets, the degraded globefishes, and the specialized flounders. As for the most part these are spiny-rayed fishes, Cuvier's name Acanthopterygii, or Acanthopteri, will serve us as well as any. The Physoclysti of Müller, the Thoracices of older authors, and the Ctenoidei of Agassiz include substantially the same series of forms. The order Teleocephali of Gill (τελεός, perfect; κεφαλή, head) has been lately so restricted as to cover nearly the same ground. In Gill's most recent catalogue of families, the order Teleocephali includes the Haplomi and rejects the Hemibranchii, Lophobranchii, Plectognathi, and Pediculati, all of these being groups characterized by sharply defined but comparatively recent characters not of the highest importance. As originally arranged, the order Teleocephali included the soft-rayed fishes as well. From it the Ostariophysi were first detached, and still later the Isospondyli were regarded by Dr. Gill as a separate order.

We may first take up serially as suborders the principal groups which serve to effect the transition from soft-rayed to spiny-rayed fishes.

Suborder Synentognathi.—Among the transitional forms between the soft-rayed and the spiny-rayed fishes, one of the most important groups is that known as Synentognathi (σύν, together; ἔν, within; γνάθος, jaw). These have, in brief, the fins and shoulder-girdle of Haplomi, the ventral fins abdominal, the dorsal and anal without spines. At the same time, as in the spiny-rayed fishes, the air-bladder is without duct and the pectoral fins are inserted high on the side of the body. With these traits are two others which characterize the group as a suborder. The lower pharyngeal bones are solidly united into one bone and the lateral line forms a raised ridge along the lower side of the body. These forms are structurally allied to the pikes (Haplomi), on the one hand, and to the mullets (Percesoces), on the other, and this relationship accords with their general appearance. In this group as in all the remaining 210families of fishes, there is no mesocoracoid, and in very nearly all of these families the duct to the air-bladder disappears at an early stage of development.

Fig. 165.—Needle-fish, Tylosurus acus (Lacépède). New York.

The Garfishes: Belonidæ.—There are two principal groups or families among the Synentognathi, the Belonidæ, with strong jaws and teeth, and the Exocœtidæ, in which these structures are feeble. Much more important characters appear in the anatomy. In the Belonidæ the third upper pharyngeal is small, with few teeth, and the maxillary is firmly soldered to the premaxillary. The vertebræ are provided with zygapophyses. The species of Belonidæ are known as garfishes, or needle-fishes. They resemble the garpike in form, but have nothing else in common. The body is long and slender, covered with small scales. Sharp, unequal teeth fill the long jaws and the dorsal is opposite the anal, on the hinder part of the body. These fishes are green in color, even the bones being often bright green, while the scales on the sides have a silvery luster. The species are excellent as food, the green color being associated with nothing deleterious. All are very voracious and some of the larger species, 5 or 6 feet long, may be dangerous even to man. Fishermen have been wounded or killed by the thrust of the sharp snout of a fish springing into the air. The garfishes swim near the surface of the water and often move with great swiftness, frequently leaping from the water. The genus Belone is characterized by the presence of gill-rakers. Belone belone is a small garfish common in southern Europe. Belone platura occurs in Polynesia. The American species (Tylosurus) lack gill-rakers. Tylosurus marinus, the common garfish of 211the eastern United States, often ascends the rivers. Tylosurus raphidoma, Tylosurus fodiator, Tylosurus acus, and other species are very robust, with short strong jaws. Athlennes hians is a very large fish with the body strongly compressed, almost ribbon-like. It is found in the West Indies and across the Isthmus as far as Hawaii. Many other species, mostly belonging to Tylosurus, abound in the warm seas of all regions. Tylosurus ferox is the long tom of the Australian markets. Potamorrhaphis with the dorsal fin low is found in Brazilian rivers. A few fossil species are referred to Belone, Belone flava from the lower Eocene being the earliest.

The Flying-fishes: Exocœtidæ.—The family of Exocœtidæ includes the flying-fishes and several related forms more or less intermediate between these and the garfishes. In these fishes the teeth are small and nearly equal and the maxillary is separate from the premaxillary. The third upper pharyngeal is much enlarged and there are no zygapophyses to the vertebræ.

The skippers (Scombresox) have slender bodies, pointed jaws, and, like the mackerel, a number of detached finlets behind dorsal and anal, although in other respects they show no affinity to the mackerel. The common skipper, or saury (Scombresox saurus), is found on both shores of the North Atlantic swimming in large schools at the surface of the water, frequently leaping for a little distance like the flying-fish. They are pursued by the mackerel-like fishes, as the tunny or bonito, and sometimes by porpoises. According to Mr. Couch, the skippers, when pursued, "mount to the surface in multitudes and crowd on each other as they press forward. When still more closely pursued, they spring to the height of several feet, leap over each other in singular confusion, and again sink beneath. Still further urged, they mount again and rush along the surface, by repeated starts, for more than one hundred feet, without once dipping beneath or scarcely seeming to touch the water. At last the pursuer springs after them, usually across their course, and again they all disappear together. Amidst such multitudes—for more than twenty thousand have been judged to be out of the water together—some must fall a prey to the enemy; but so many hunting in company, it must be long before the pursuers abandon. From inspection we could scarcely judge 212the fish to be capable of such flights, for the fins, though numerous, are small, and the pectoral far from large, though the angle of their articulation is well adapted to raise the fish by the direction of their motions to the surface."

A similar species, Cololabis saira, with the snout very much shorter than in the Atlantic skipper, is the Samma of the fishermen of Japan.

The hard-head (Chriodorus atherinoides) has no beak at all and its tricuspid incisor teeth are fitted to feed on plants. In this genus, as in the flying-fishes, there are no finlets. The hard-head is an excellent food-fish abundant about the Florida Keys but not yet seen elsewhere.

Fig. 166.—Saury, Scombresox saurus (L.). Wood's Hole.

Fig. 167.—Halfbeak, Hyporhamphus unifasciatus (Ranzani). Chesapeake Bay.

Another group between the gars and the flying-fishes is that of the halfbeaks, or balaos, Hemirhamphus, etc. These are also vegetable feeders, but with much smaller teeth, and the lower jaw with a spear-like prolongation to which a bright-red membrane is usually attached. Of the halfbeaks there are several genera, all of the species swimming near the surface in schools and sometimes very swiftly. Some of them leap into the air and sail for a short distance like flying-fishes, with which group the halfbeaks are connected by easy gradations. The commonest species along our Atlantic coast is Hyporhamphus unifasciatus; a larger species, Hemirhamphus brasiliensis, abounds about the Florida Keys. Euleptorhamphus longirostris, a ribbon-shaped elongate fish, with long jaw and long pectorals, is taken in the open sea, both in the Atlantic and Pacific, being common in Hawaii. The Asiatic genus Zenarchopterus is viviparous, 213having the anal fin much modified in the male, forming an intromittent organ, as in the Pœciliidæ. One species occurs in the river mouths in Samoa.

The flying-fishes have both jaws short, and at least the pectoral fins much enlarged, so that the fish may sail in the air for a longer or shorter distance.

Fig. 168.—Sharp-nosed Flying-fish, Fodiator acutus (Val.). Panama.

The smaller species have usually shorter fins and approach more nearly to the halfbeaks. Fodiator acutus, with sharp jaws, and Hemiexocœtus, with a short beak on the lower jaw, are especially intermediate. The flight of the flying-fishes is described in detail on p. 157, Vol. I.

The Catalina flying-fish, Cypselurus californicus, of the shore of southern California is perhaps the largest of the known species, reaching a length of 18 inches. To this genus, Cypselurus, having a long dorsal and short anal, and with ventrals enlarged as well as pectorals, belong all the species strongest in flight, Cypselurus heterurus and furcatus of the Atlantic, Cypselurus simus of Hawaii and Cypselurus agoo in Japan. The very young of most of these species have a long barbel at the chin which is lost with age.

In the genus Exonautes the base of anal fin is long, as long as that of the dorsal. The species of this group, also strong in flight, are widely distributed. Most of the European flying-fishes, as Exonautes rondeleti, Exonautes speculiger, and Exonautes vinciguerræ, belong to this group, while those of Cypselurus mostly inhabit the Pacific. The large Australian species Exonautes unicolor, Fig. 226, Vol. I, belongs to this group. In the restricted genus Exocœtus the ventral fins are short and not used in flight. Exocœtus volitans (evolans) is a small flying-fish, 214with short ventral fins not used for flight. It is perhaps the most widely distributed of all, ranging through almost all warm seas. Parexocœtus brachypterus, still smaller, and with shorter, grasshopper-like wings, is also very widely distributed. An excellent account of the flying-fishes of the world has been given by Dr. C. F. Lütken (1876), the University of Copenhagen, which institution has received a remarkably fine series from trading-ships returning to that port. Later accounts have been given by Jordan and Meek, and by Jordan and Evermann.

Fig. 169.—Catalina Flying-fish, Cypselurus californicus (Cooper). Santa Barbara.

Very few fossil Exocœtidæ are found. Species of Scombresox and Hemirhamphus are found in the Tertiary, the earliest being Hemirhamphus edwardsi from the Eocene of Monte Bolca. No fossil flying-fishes are known, and the genera, Exocœtus, Exonautes, and Cypselurus are doubtless all of very recent origin.

Suborder Percesoces.—In the line of direct ascending transition from the Haplomi and Synentognathi, the pike and flying-fish, towards the typical perch-like forms, we find a number of families, perch-like in essential regards but having the ventral fins abdominal.

These types, represented by the mullet, the silverside, and the barracuda, have been segregated by Cope as an order called Percesoces (Perca, perch; Esox, pike), a name which correctly describes their real affinities. In these typical forms, mullet, silverside, and barracuda, the affinities are plain, but in other transitional forms, as the threadfin and the stickleback, the relationships are less clear. Cope adds to the series of Percesoces the Ophiocephalidæ, which Gill leaves with the Anabantidæ among the spiny-rayed forms. Boulenger adds also the sand-lances (Ammodytidæ) and the threadfins (Polynemidæ), while Woodward places here the Crossognathidæ. In the present work we define the Percesoces so as to include all spiny-rayed fishes in which the ventral fins are naturally abdominal, excepting those having a reduced number of gill-bones, or of actinosts, or other peculiarities of the shoulder-girdle. The Ammodytidæ have no real affinities with the Percesoces. The Crossognathidæ and other families with abdominal ventrals and the dorsal spines wholly obsolete may belong with the Haplomi. Boulenger places the Chiasmodontidæ, the Stromateidæ, and the Tetragonuridæ among the Percesoces, an arrangement of very doubtful validity. In most of the Percesoces the scales are cycloid, the spinous dorsal forms a short separate fin, and in all the air-duct is wanting.

The Silversides: Atherinidæ.—The most primitive of living Percesoces constitute the large family of silversides (Atherinidæ), 216known as "fishes of the King," Pescados del Rey, Pesce Rey, or Peixe Re, wherever the Spanish or Portuguese languages are spoken. The species are, in general, small and slender fishes of dry and delicate flesh, feeding on small animals. The mouth is small, with feeble teeth. There is no lateral line, the color is translucent green, with usually a broad lateral band of silver. Sometimes this is wanting, and sometimes it is replaced by burnished black. Some of the species live in lakes or rivers, others in bays or arms of the sea, but never at a distance from the shore or in water of more than a few feet in depth. The larger species are much valued as food, the smaller ones, equally delicate, are fried in numbers as "whitebait," but the bones are firmer and more troublesome than in the smelts and young herring. The species of the genus Atherina, known as "friars," or "brit," are chiefly European, although some occur in almost all warm or temperate seas. These are small fishes, with the mouth relatively large and oblique and the scales rather large and firm. Atherina hepsetus and A. presbyter are common in Europe, Atherina stipes in the West Indies, Atherina bleekeri in Japan, and Atherina insularum and A. lacunosa in Polynesia. The genus Chirostoma contains larger species, with projecting lower jaw, abounding in the lakes of Mexico. Chirostoma humboldtianum is very abundant about Mexico City. Like all the other species of this genus it is remarkably excellent as food, the different species constituting the famous "Pescados Blancos" of the great lakes of Chapala and Patzcuaro of the western slope of Mexico. A very unusual circumstance is this: that numerous very closely related species occupy the same waters and are taken in the same nets. In zoology, generally, it is an almost universal rule that very closely related species occupy different geographical areas, their separation being due to barriers which prevent interbreeding. But in the lake of Chapala, near Guadalajara, Prof. John O. Snyder and the present writer, and subsequently Dr. S. E. Meek, found ten distinct species of Chirostoma, all living together, taken in the same nets and scarcely distinguishable except on careful examination. Most of these species are very abundant throughout the lake, and all reach a length of twelve to fifteen inches. These species are Chirostoma estor, Ch. lucius, Ch. sphyræna, 217Ch. ocotlane, Ch. lermæ, Ch. chapalæ, Ch. grandocule, Ch. labarcæ, Ch. promelas, and Ch. bartoni. A similar assemblage of species nearly all different from these was obtained by Dr. Seth E. Meek in the lake of Patzcuaro, farther south. In this lake were found Ch. attenuatum, Ch. patzcuaro, Ch. humboldtianum, Ch. grandocule, and Ch. estor. The lake of Zirahuen, near Chapala, contains Ch. estor and Ch. zirahuen.

Fig. 170.—Pescado blanco, Chirostoma humboldtianum (Val.). Lake Chalco, City of Mexico.

Fig. 171.—Silverside or Brit, Kirtlandia vagrans (Goode & Bean). Pensacola.

Still another species, Ch. jordani, is found about the city of Mexico, where it is sold baked in corn-husks. Along the coasts of Peru, Chile, and Argentina is found still another assemblage of fishes of the king, with very small scales, constituting the genera Basilichthys and Gastropterus (Pisciregia). Basilichthys microlepidotus is the common Pesca del Rey of Chile. The small silversides, or "brit," of our Atlantic coast belong to numerous species of Menidia, Menidia notata to the northward and Menidia menidia to the southward being most abundant. Kirtlandia laciniata, with ragged scales, is common along the Virginia coast, and K. vagrans farther south. Another small species, very slender and very graceful, is the brook silverside 218Labidesthes sicculus, which swarms in clear streams from Lake Ontario to Texas. This species, three to four inches long, has the snout produced and a very bright silvery stripe along the side. Large and small species of silversides occur in the sea along the California coast, where they are known familiarly as "blue smelt" or "Peixe Re." The most important of these and the largest member of the family, reaching a length of eighteen inches, is Atherinopsis californiensis, an important food-fish throughout California, everywhere wrongly known as smelt. Atherinops affinis is much like it, but has Y-shaped teeth. Iso flos-maris, called Nami-no-hana, or flower of the surf, is a shining little fish with belly shape like that of a herring. It lives in the surf on the coast of Japan. Melanotænia nigrans of Australia (family Melanotæniidæ) has the lateral band jet-black, as has also Melaniris balsanus of the rivers of southern Mexico. Atherinosoma vorax of Australia has strong teeth like those of a barracuda.

Fig. 172.—Blue Smelt or Pez del Rey, Atherinopsis californiensis Girard. San Diego.

Fig. 173.—Flower of the waves, Iso flos-maxis, Jordan & Starks. Enoshima, Japan.

Fossil species of Atherina occur in the Italian Eocene, the best known being Atherina macrocephala. Another species, Rhamphognathus paralepoides, allied to Menidia, occurs in the Eocene of Monte Bolca.

219The Mullets: Mugilidæ.—The mullets (Mugilidæ) are more clumsy in form than the silversides, robust, with broad heads and stouter fin-spines. The ventral fins are abdominal but well forward, the pelvis barely touching the clavicle, a condition to be defined as "subabdominal." The small mouth is armed with very feeble teeth, often reduced to mere fringes. The stomach is muscular like the gizzard of a fowl and the species feed largely on the vegetation contained in mud. There are numerous species, mostly living in shallow bays and estuaries, but some of them are confined to fresh waters. All are valued as food and some of them under favorable conditions are especially excellent.

Most of the species belong to the genera Mugil, the mullet of all English-speaking people, although not at all related to the red mullet or surmullet of the ancient Romans, Mullus barbatus.

The mullets are stoutish fish from one to two feet long, with blunt heads, small mouths almost toothless, large scales, and a general bluish-silvery color often varied by faint blue stripes. The most important species is Mugil cephalus, the common striped mullet. This is found throughout southern Europe and from Cape Cod to Brazil, from Monterey, California, to Chile, and across the Pacific to Hawaii, Japan, and the Red Sea. Among specimens from all these regions we can detect no difference.

Professor Goode gives the following account of its habits:

"The large mullets begin to assemble along the Florida coast in schools in the height of summer, probably preparatory to spawning, and at this time the eggs commence to mature. In this season they swim at the surface, and are then pursued by enemies in the water and the air, and also fall an easy prey to the fishermen. They appear to prefer to swim against the wind, and school best with a northeast wind. They also run against the tide. In Florida the spawning season seems to extend from the middle of November to the middle of January. Some of the fishermen say that they go on the mud-flats and oyster-beds at the mouth of the river to deposit their eggs. What becomes of them after this no one seems to know, but it is probable that they spread themselves over the whole surface of water-covered country in such a manner as not to be 220perceptible to the fisherman, who makes no effort at this time to secure the spent, lean fish. Many of them probably find their way to the lakes and others remain wherever they find good feeding-ground, gathering flesh and recruiting strength for the great strain of the next spawning season."

Professor Goode informs us that the fishermen recognize "three distinct periods of schooling and separate runs of mullet. To what extent these are founded on tradition, or upon the necessity of change in the size of the mesh of their nets, it is impossible to say. The 'June mullet' average about five to the pound; the 'fat mullet,' which are taken from August 20 to October 1, weigh about two pounds; these have, the fishermen say, a 'roe of fat' on each side as thick as a man's thumb. The 'roe mullet' weigh about two and a half pounds and are caught in November and until Christmas. Between the seasons of 'fat mullet' and 'roe mullet' there is an intermission of two or three weeks in the fishing." Professor Goode hazards the suggestion that "the 'fat mullet' of September are the breeding fish of November, with roes in an immature state, the ova not having become fully differentiated."

The mullet feed on the bottom in quiet water, swimming head downward. The food is sifted over in the mouth, the mud rejected, and the plants, chiefly microscopic, retained. Mr. Silas Stearns compares a school of mullets to barnyard fowls feeding together. When a fish finds a rich spot the others flock about it as chickens do. The pharyngeals form a sort of filter, stopping the sand and mud, the coarse parts being ejected through the mouth. Dr. Günther thus describes this apparatus:

"The upper pharyngeals have a rather irregular form: they are slightly arched, the convexity being directed toward the pharyngeal cavity, tapering anteriorly and broad posteriorly. They are coated with a thick, soft membrane, which reaches far beyond the margin of the bone and is studded all over with minute horny cilia. Each branchial arch is provided with a series of long gill-rakers, which are laterally bent downward, each series closely fitting to the sides of the adjoining arch; they constitute together a sieve admirably adapted to permit a transit for the water, retaining at the same time every solid substance in the cavity of the pharynx."

221The young mullet feed in schools and often swim with the head at the surface of the water.

Fig. 174.—Striped Mullet, Mugil cephalus (L.). Wood's Hole, Mass.

We are not able to distinguish from the common striped mullet of Europe and America the mullet of Hawaii, the famous Ama-ama, the most valued of Hawaiian fishes. This species is reared in mullet ponds, made by extending a stone wall across an arm of the sea. Through openings in the wall the young mullet enter, and in its protection they grow very fat on the abundant algæ and other vegetation. They thus become the most plentiful and most esteemed of the market fishes of Honolulu. The Awa (Chanos) and the Awa-awa (Elops) also enter these ponds and are reared with the mullet, being similarly but less valued. Unfortunately the kaku, or small barracuda (Sphyræna helleri), also enters with these helpless fishes and destroys many of the smaller individuals. Another striped species, also very similar to Mugil cephalus in appearance and value, in fact indistinguishable from the Hawaiian mullet, abounds in Japan and India.

The white or unstriped mullets are generally smaller, but otherwise differ little. Mugil curema is the white mullet of tropical America, ranging occasionally northward, and several other species occur in the West Indies and the Mediterranean. The genus Mugil has the eye covered by thick transparent tissue called the adipose eyelid. In Liza the adipose eyelid is wanting. Liza capito, the big-headed mullet of the Mediterranean, is a well-known species. Most of the mullets of the south seas belong to the genus Liza. Liza melinoptera and Liza 222cæruleomaculata are common in Samoa. The genus Querimana includes dwarf-mullets, two or three inches long, known as whirligig-mullets. These little fishes gather in small schools and swim round and round on the surface like the whirligig-beetles, or Gyrinidæ, their habits being like those of the young mullets; some young mullets having been, in fact, described as species of Querimana. The genus Agonostomus includes fresh-water mullets of the mountain rivers of the East and West Indies and Mexico, locally known as trucha, or trout. Agonostomus nasutus of Mexico is the best-known species.

Fig. 175.—Joturo or Bobo, Joturus pichardi Poey. Rio Bayano, Panama.

The Joturo, or Bobo, Joturus pichardi, is a very large robust and vigorous mullet which abounds at the foot of waterfalls in the mountain torrents of Cuba, eastern Mexico, and Central America. It is a good food-fish, frequently taken about Jalapa, Havana, and on the Isthmus of Panama. Its lips are very thick and its teeth are broad, serrated, loosely inserted incisors.

Fossil mullets are few. Mugil radobojanus is the earliest from the Miocene of Croatia.

The Barracudas: Sphyrænidæ.—The Sphyrænidæ, or barracudas, differ from the mullets in the presence of very strong teeth in the bones of the large mouth. The lateral line is also developed, there is no gizzard, and there are numerous minor modifications connected with the food and habits. The species are long, slender swift fishes, powerful in swimming and voracious to the last degree. Some of the species reach a length of six feet or more, and these are almost as dangerous to bathers 223as sharks would be. The long, knife-like teeth render them very destructive to nets. The numerous species are placed in the single genus Sphyræna, and some of them are found in all warm seas, where they feed freely on all smaller fishes, their habits in the sea being much like those of the pike in the lakes. The flesh is firm, delicate, and excellent in flavor. In the larger species, especially in the West Indies, it may be difficult of digestion and sometimes causes serious illness, or "ichthyosism."

Fig. 176.—Barracuda, Sphyræna barracuda Walbaum. Florida.

Sphyræna sphyræna is the spet, or sennet, a rather small barracuda common in southern Europe. Sphyræna borealis of our eastern coast is a similar but still feebler species rarely exceeding a foot in length. These and other small species are feeble folk as compared with the great barracuda (Sphyræna barracuda) of the West Indies, a robust savage fish, also known as picuda or becuna. Sphyræna commersoni of Polynesia is a similar large species, while numerous lesser ones occur through the tropical seas. On the California coast Sphyræna argentea is an excellent food-fish, slenderer than the great barracuda but reaching a length of five feet.

Several species of fossil barracuda occur in the Italian Eocene, Sphyræna bolcensis being the earliest.

Stephanoberycidæ.—We may append to the Percesoces, for want of a better place, a small family of the deep sea, its affinities at present unknown. The Stephanoberycidæ have the ventrals I, 5, subabdominal, a single dorsal without spine, and the scales cycloid, scarcely imbricated, each with one or two central spines. The mouth is large, with small teeth, the skull cavernous, as in the berycoids, from which group the normally formed ventrals abdominal in position would seem to exclude it. Stephanoberyx monæ and S. gilli are found at the depth of a mile and a half below the Gulf Stream. Boulenger first placed 224them with the Percesoces, but more recently suggests their relationship with the Haplomi. Perhaps, as supposed by Gill, they may prove to be degenerate berycoids in which the ventral fins have lost their normal connection.

Crossognathidæ.—A peculiar primitive group referred by Woodward to the Percesoces is the family of Crossognathidæ of the Cretaceous period. As in these fishes there are no fin-spines, they may be perhaps better placed with the Haplomi. The dorsal fin is long, without distinct spines, and the abdominal ventrals have six to eight rays. The mouth is small, with feeble teeth, and the body is elongate and compressed. Crossognathus sabandianum occurs in the Cretaceous of Switzerland and Germany, Syllæmus latifrons and other species in the Colorado Cretaceous, and Syllæmus anglicus in England. The Crossognathidæ have probably the lower pharyngeals separate, else they would be placed among the Synentognathi, a group attached by Woodward, not without reason, to the Percesoces.

Cobitopsidæ.—Near the Crossognathidæ may be placed the extinct Cobitopsidæ, Cobitopsis acuta being recorded from the Oligocene of Puy-de-Dôme in France. In this species there is a short dorsal fin of about seventeen rays, no teeth, and the well-developed ventral fins are not far in front of the anal. This little fish bears a strong resemblance to Ammodytes, but the affinities of the latter genus are certainly with the ophidioid fishes, while the real relationship of Cobitopsis is uncertain.

Fig. 177.—Cobitopsis acuta Gervais, restored. Oligocene of Puy-de-Dôme. (After Woodward.)

Suborder Rhegnopteri.—The threadfins (Polynemidæ) are allied to the mullets, but differ from them and from all other fishes in the structure of the pectoral fin and its basal bones, or actinosts.

225

Fig. 178.—Shoulder-girdle of a Threadfin, Polydactylus approximans (Lay & Bennett).

Fig. 179.—Threadfin, Polydactylus octonemus (Girard). Pensacola.

The pectoral fin is divided into two parts, the lower composed of free or separate rays very slender and thread-like, sometimes longer than the body. Two of the actinosts of the pectoral support the fin, one is slender and has no rays, while the fourth is plate-like and attached to the coracoids, supporting the pectoral filaments. The body is rather robust, covered with large scales, formed much as in the mullet. The lateral line extends on the caudal fin as in the Sciænidæ which group these fishes resemble in many ways. The mouth is large, inferior, with small teeth. The species are carnivorous fishes of excellent flesh, abounding on sandy shores in the warm seas. They are not very active and not at all voracious. The coloration is bluish and silvery, sometimes striped with black. Most of the species belong to the genus Polydactylus. Polydactylus 226virginicus, the barbudo, with seven filaments, is common in the West Indies and Florida. Polydactylus octonemus with eight filaments is more rare, but ranges further north. Polydactylus approximans, the raton of western Mexico, with six filaments, reaches San Diego. Polydactylus plebejus is common in Japan and other species range through Polynesia. In India isinglass is made from the large air-bladder of species of Polydactylus. The rare Polynemus quinquarius of the West Indies have five pectoral filaments, these being greatly elongate, much longer than the body.

No extinct Polynemidæ are recorded.

Fig. 180.—Shoulder-girdle of a Stickleback, Gasterosteus aculeatus Linnæus. (After Parker.)

Fig. 181.—Shoulder-girdle of Fistularia petimba Lacépède, showing greatly extended interclavicle, the surface ossified.

Suborder Hemibranchii.—Still another transitional group, the Hemibranchii, is composed of spiny-rayed fishes with abdominal ventrals. In this suborder there are other points of divergence, though none of high importance. In these fishes the bones of the shoulder-girdle are somewhat distorted, the supraclavicle reduced or wanting, and the gill structures somewhat degenerate. The presence of bones called interclavicles or infraclavicles, below and behind the clavicle, has been supposed to characterize the order of Hemibranchii. But this character has very slight importance. In two families, Macrorhamphosidæ and Centriscidæ, the interclavicles are absent altogether. In the Fistulariidæ they are very large. According to the studies of Mr. Edwin C. Starks, the bone in question is not a true infraclavicle. It is not identical with the infraclavicle of the Ganoids, but it is only a backward extension of the hypocoracoid, there being no suture between 228the two bones. In those species which have bony plates instead of scales, this bone has a deposit of bony substance or ganoid enamel at the surface. This gives it an apparent prominence as compared with other bones of the skeleton, but it has no great taxonomic importance. Dr. Hay unites the suborders Hemibranchii, Lophobranchii, and Hypostomides to form the order Phthinobranchii (φθινάς, waning; βράγχος, gill), characterized by the reduction of the gill-arches. These forms are really nearly related, but their affinities with the Percesoces are so close that it may not be necessary to form a distinct order of the combined group. Boulenger unites the Hemibranchii with Lampris to form a group, Catosteomi, characterized by the development of infraclavicles; but we cannot see that Lampris bears any affinity to the sticklebacks, or that the presence of infraclavicle has any high significance, nor is it the supposed infraclavicle of Lampris homologous with that of the Hemibranchii. The dorsal fin in the Hemibranchii has more or less developed spines; spines are also present in the ventral fins. The lower pharyngeals are separated; there is no air-duct. The mouth is small and the bones of the snout are often much produced. The preopercle and symplectic are distinct. The group is doubtless derived from some transitional spiny-rayed type allied to the Percesoces. The Lophobranchs, another supposed order, represent simply a still further phase of degradation of gills and ventral fins. Dr. Gill separates these two groups as distinct orders and places them, as aberrant offshoots, near the end of his series of bony fishes. We prefer to leave them with the other transitional forms, not regarding their traits of divergence as of any great importance in the systematic arrangement of families.

The Sticklebacks: Gasterosteidæ.—The sticklebacks (Gasterosteidæ) are small, scaleless fishes, closely related to the Fistulariidæ so far as anatomy is concerned, but with very different appearance and habits. The body often mailed, the dorsal is preceded by free spines and the ventrals are each reduced to a sharp spine with a rudimentary ray. The jaws are short, bristling with sharp teeth, and these little creatures are among the most active, voracious, and persistent of all fishes. They attack the fins of larger fishes, biting off pieces, 229and at the same time they devour the eggs of all species accessible to them. In almost all fresh and brackish waters of the north temperate zone these little fishes abound. "It is scarcely to be conceived," Dr. Günther observes, "what damage these little fishes do, and how greatly detrimental they are to the increase of all the fishes among which they live, for it is with the utmost industry, sagacity, and greediness that they seek out and destroy all the young fry that come their way."

The sticklebacks inhabit brackish and fresh waters of the northern hemisphere, species essentially alike being found throughout northern Europe, Asia, and America. The same species is subject to great variation. The degree of development of spines and bony plates is greatest in individuals living in the sea and least in clear streams of the interior. Each of the mailed species has its series of half-mailed or even naked varieties found in the fresh waters. This is true in Europe, New England, California, and Japan. The farther the individuals are from the sea, the less perfect is their armature. Thus, Gasterosteus cataphractus, which in the sea has a full armature of bony plates on the side, about 30 in number, will have in river mouths from 6 to 20 plates and in strictly fresh water only 2 or 3 or even none at all.

The sticklebacks have been noted for their nest-building habits. The male performs this operation, and he is provided with a special gland for secretion of the necessary cement. Dr. Gill quotes from Dr. John A. Ryder an account of this process. The secretory gland is a "large vesicle filled with a clear secretion which coagulates into threads upon contact with water. It appears to open directly in front of the vent. As soon as it is ruptured, it loses its transparency, and whatever secretion escapes becomes whitish after being in contact with water for a short time. This has the same tough, elastic qualities as when spun by the animal itself, and is also composed of numerous fibers, as when a portion is taken that has been recently spun upon the nest. Thus provided, when the nuptial season has arrived the male stickleback prepares to build his nest, wherein his mate may deposit her eggs. How this nest is built, and the subsequent proceedings of the sticklebacks, have been told us in a graphic manner by Mr. John K. 230Lord, from observations on Gasterosteus cataphractus on Vancouver Island, although the source of his secretion was misunderstood:

"The site is generally amongst the stems of aquatic plants, where the water always flows but not too swiftly. He first begins by carrying small bits of green material which he nips off the stalks and tugs from out the bottom and sides of the bank; these he attaches by some glutinous material, that he clearly has the power of secreting, to the different stems destined as pillars for his building. During this operation he swims against the work already done, splashes about, and seems to test its durability and strength; rubs himself against the tiny kind of platform, scrapes the slimy mucus from his sides to mix with and act as mortar for his vegetable bricks. Then he thrusts his nose into the sand at the bottom, and, bringing a mouthful, scatters it over the foundation; this is repeated until enough has been thrown on to weight the slender fabric down and give it substance and stability. Then more twists, turns, and splashings to test the firm adherence of all the materials that are intended to constitute the foundation of the house that has yet to be erected on it. The nest, or nursery, when completed is a hollow, somewhat rounded, barrel-shaped structure worked together much in the same way as the platform fastened to the water-plants; the whole firmly glued together by the viscous secretion scraped from off the body. The inside is made as smooth as possible by a kind of plastering system; the little architect continually goes in, then, turning round and round, works the mucus from his body on to the inner sides of the nest, where it hardens like tough varnish. There are two apertures, smooth and symmetrical as the hole leading into a wren's nest, and not unlike it.

"All this laborious work is done entirely by the male fish, and when completed he goes a-wooing. Watch him as he swims towards a group of the fair sex enjoying themselves amidst the water-plants arrayed in his best and brightest livery, all smiles and amiability; steadily and in the most approved style of stickleback love-making this young and wealthy bachelor approaches the object of his affections, most likely tells her all about his house and its comforts, hints 231delicately at his readiness and ability to defend her children against every enemy, vows unfailing fidelity, and in lover fashion promises as much in a few minutes as would take a lifetime to fulfill. Of course she listens to his suit; personal beauty, indomitable courage, backed by the substantial recommendations of a house ready built and fitted for immediate occupation, are gifts not to be lightly regarded.

"Throwing herself on her side the captive lady shows her appreciation, and by sundry queer contortions declares herself his true and devoted spouse. Then the twain return to the nest, into which the female at once betakes herself and therein deposits her eggs, emerging, when the operation is completed, by the opposite hole. During the time she is in the nest (about six minutes) the male swims round and round, butts and rubs his nose against it, and altogether appears to be in a state of defiant excitement. On the female leaving, he immediately enters, deposits the milt on the eggs, taking his departure through the back door. So far his conduct is strictly pure; but I am afraid morality in stickleback society is of rather a lax order. No sooner has this lady, his first love, taken her departure, than he at once seeks another, introduces her as he did the first, and so on, wife after wife, until the nest is filled with eggs, layer upon layer, milt being carefully deposited betwixt each stratum of ova. As it is necessary there should be two holes, by which ingress and egress can be readily accomplished, so it is equally essential in another point of view. To fertilize fish-eggs, running water is the first necessity; and, as the holes are invariably placed in the direction of the current, a steady stream of water is thus directed over them."

To the genus Gasterosteus the largest species belong, those having three dorsal spines, and the body typically fully covered with bony plates. Gasterosteus aculeatus inhabits both shores of the Atlantic and the scarcely different Gasterosteus cataphractus swarms in the inlets from southern California to Alaska, Siberia, and northern Japan. Half-naked forms have been called by various names and one entirely naked in streams of southern California is named Gasterosteus williamsoni. Its traits are, however, clearly related to its life in fresh waters.

In Pygosteus pungitius, a type of almost equally wide range, 232there are nine or ten dorsal spines and the body is more slender. All kinds of waters of the north on both continents may yield this species or its allies and variations, mailed or naked. The naked, Apeltes quadracus, is found in the sea only, along the New England coast.

Fig. 182.—Three-spined Stickleback, Gasterosteus aculeatus L. Wood's Hole, Mass.

Fig. 183.—Four-spined Stickleback, Apeltes quadracus Mitchill. Wood's Hole, Mass.

Eucalia inconstans is the stickleback of the clear brook from New York to Indiana and Minnesota. The male is jet black in spring with the sheen of burnished copper and he is intensely active in his work of protecting the eggs of his own species and destroying the eggs and fry of others. Spinachia spinachia is a large sea stickleback of Europe with many dorsal spines.

No fossil Gasterosteidæ are recorded, and the family, while the least specialized in most regards, is certainly not the most primitive of the suborder.

The Aulorhynchidæ.—Closely related to the sticklebacks is the small family of Aulorhynchidæ, with four soft rays in the 233ventral fins. Aulorhynchus, like Spinachia, has many dorsal spines and an elongate snout approaching that of a trumpet-fish. Aulorhynchus flavidus lives on the coast of California and Aulichthys japonicus in Japan. The extinct family of Protosyngnathidæ is near Aulorhynchus, with the snout tubular, the ribs free, not anchylosed as in Aulorhynchus, and with the first vertebræ fused, forming one large one as in Aulostomus. Protosyngnathus sumatrensis occurs in Sumatra. Protaulopsis bolcensis of the Eocene of Italy has the ventral fins farther back, and is probably more primitive than the sticklebacks.

Cornet-fishes: Fistulariidæ.—Closely related to the sticklebacks so far as structure is concerned is a family of very different habit, the cornet-fishes, or cornetas (Fistulariidæ). In these fishes the body is very long and slender, like that of a garfish. The snout is produced into a very long tube, which bears the short jaws at the end. The teeth are very small. There are no scales, but bony plates are sunk in the skin. The ventrals are abdominal, each with a spine and four rays. The four anterior vertebræ are very much elongate. There are no spines in the dorsal and the back-bone extends through the forked caudal, ending in a long filament. The cornet-fishes are dull red or dull green in color. They reach a length of two or three feet, and the four or five known species are widely distributed through the warm seas, where they swim in shallow water near the surface. Fistularia tabaccaria, the tobacco-pipe fish, is common in the West Indies, Fistularia petimba, F. serrata, and others in the Pacific. A fossil cornet-fish of very small size, Fistularia longirostris, is known from the Eocene of Monte Bolca, near Verona. Fistularia kœnigi is recorded from the Oligocene of Glarus.

The Trumpet-fishes: Aulostomidæ.—The Aulostomidæ, or trumpet-fishes are in structure entirely similar to the Fistulariidæ, but the body is band-shaped, compressed, and scaly, the long snout bearing the feeble jaws at the end. There are numerous dorsal spines and no filament on the tail. Aulostomus chinensis (maculatus) is common in the West Indies, Aulostomus valentini abounds in Polynesia and Asia, where it is a food-fish of moderate importance. A species of Aulostomus (bolcensis) is found in the Italian Eocene. Allied to it is 234the extinct family Urosphenidæ, scaleless, but otherwise similar. Urosphen dubia occurs in the Eocene at Monte Bolca. Urosphen is perhaps the most primitive genus of the whole suborder of Hemibranchii.

Fig. 184.—Trumpet-fish, Aulostomus chinensis (L.) Virginia.

The Snipefishes: Macrorhamphosidæ.—Very remarkable fishes are the snipefishes, or Macrorhamphosidæ. In these forms the snout is still tubular, with the short jaws at the end. The body is short and deep, partly covered with bony plates. The dorsal has a very long serrated spine, besides several shorter ones, and the ventral fins have one spine and five rays.

Fig. 185.—Japanese Snipefish, Macrorhamphosus sagifue Jordan & Starks. Misaki, Japan.

The snipefish, or woodcock-fish, Macrorhamphosus scolopax, is rather common on the coasts of Europe, and a very similar species (M. sagifue) occurs in Japan. The Rhamphosidæ, represented by Rhamphosus, an extinct genus with the ventrals further forward, are found in the Eocene rocks of Monte Bolca. Rhamphosus vastrum has minute scales, short dorsal, and the snout greatly attenuate.

The Shrimp-fishes: Centriscidæ.—One of the most extraordinary types of fishes is the small family of Centriscidæ, found in the East Indies. The back is covered by a transparent bony cuirass which extends far beyond the short tail, on which the two dorsal fins are crowded. Anteriorly this cuirass is 235composed of plates which are soldered to the ribs. The small toothless mouth is at the end of a long snout.

Fig. 186.—Shrimp-fish, Æoliscus strigatus (Günther). Riu Kiu Islands, Japan.

These little fishes with the transparent carapace look very much like shrimps. Centriscus scutatus (Amphisile) with the terminal spine fixed is found in the East Indies, and Æoliscus strigatus with the terminal spine movable is found in southern Japan and southwards.

Fig. 187.—Æoliscus heinrichi Heckel. Eocene of Carpathia. Family Centriscidæ. (After Heckel.)

A fossil species, Æoliscus heinrichi, is found in the Oligocene of various parts of Europe, and Centriscus longirostris occurs in the Eocene of Monte Bolca.

In the Centriscidæ and Macrorhamphosidæ the expansions of the hypocoracoid called infraclavicles are not developed.

The Lophobranchs.—The suborder Lophobranchii (λοφός, tuft; βραγχός, gill) is certainly an offshoot from the Hemibranchii and belongs likewise among the forms transitional from soft to spiny-rayed fishes. At the same time it is a degenerate group, and in its modifications it turns directly away from the general line of specialization.

The chief characters are found in the reduction of the gills to small lobate tufts attached to rudimentary gill-arches. The so-called infraclavicles are present, as in most of the Hemibranchii. Bony plates united to form rings take the place of scales. The long tubular snout bears the short toothless jaws at the end. The preopercle is absent, and the ventrals are seven-rayed or wanting. The species known as pipefishes and sea-horses are all very small and none have any economic value. They are 236numerous in all warm seas, mostly living in shallow bays among seaweed and eel-grass. The muscular system is little developed and all the species have the curious habit of carrying the eggs until hatched in a pouch of skin under the belly or tail; this structure is usually found in the male.

The Solenostomidæ.—The Solenostomidæ of the East Indies are the most primitive of these fishes. They have the body rather short and provided with spinous dorsal, and ventral fins. The pretty species are occasionally swept northward to Japan in the Black Current. Solenostomus cyanopterus is a characteristic species. Solenorhynchus elegans, now extinct (with the trunk more elongate), preceded Solenostomus in the Eocene of Monte Bolca.

The Pipefishes: Syngnathidæ.—The Syngnathidæ are very long and slender fishes, with neither spinous dorsal, nor ventral fins, the body covered by bony rings. Of the pipefish, Syngnathus, there are very many species on all northern coasts. Syngnathus acus is common in Europe, Syngnathus fuscum along the New England coast, Syngnathus californiense in California, and Syngnathus schlegeli in Japan. Numerous other species of Syngnathus and other genera are found further south in the same regions. Corythroichthys is characteristic of coral reefs and Microphis of the streams of the islands of Polynesia. In general, the more northerly species have the greater number of vertebræ and of bony rings. Tiphle tiphle is a large pipefish of the Mediterranean. This species was preceded by Tiphle albyi (Siphonostoma) in the Miocene of Sicily. Other pipefishes, referred to as Syngnathus and Calamostoma, are found as fossils in Tertiary rocks.

The Sea-horses: Hippocampus.—Both fossil and recent forms constitute a direct line of connection from the pipefishes to the sea-horses. In the latter the head has the form of the head of a horse. It is bent at right angles to the body like the head of a knight at chess. There is no caudal fin, and the tail in typical species is coiled and can hardly be straightened out. Calamostoma of the Eocene, Gasterotokeus of Polynesia, and Acentronura of Japan are forms which connect the true sea-horses with the pipefish. Gasterotokeus has the long head and slender body of the pipefish, with the prehensile finless tail of a sea-horse. Most of the living species of the sea-horse belong to the genus Hippocampus. These little creatures have the egg-sac of the male under the abdomen. They range from two inches to a foot in length and some of the many species may be found in abundance in every warm sea. Some cling by the tails to floating seaweed and are swept to great distances; others cling to eel-grass and live very near the shore. The commonest European species is Hippocampus hippocampus. Most abundant on our Atlantic coast is Hippocampus hudsonius. Hippocampus coronatus is most common in Japan. The largest species are Hippocampus ingens of Lower California and Hippocampus kelloggi in Japan. Many species, especially of the smaller ones, have the spines of the bony plates of the body ending in fleshy flaps. These are sometimes so enlarged as to simulate leaves of seaweed, thus serving for the efficient protection of the species. These flaps are developed to an extreme degree in Phyllopteryx eques, a pipefish of the East Indies.

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Fig. 188.—Solenostomus cyanopterus Bleeker. Misaki, Japan.

238

Fig. 189.—Sea-horse, Hippocampus hudsonius Dekay. Virginia.

No fossil sea-horses are known.

The following account of the breeding-habits of our smallest sea-horse (Hippocampus zosteræ) was prepared by the writer for a book of children's stories:

"He was a little bit of a sea-horse and his name was Hippocampus. He was not more than an inch long, and he had a red stripe on the fin on his back, and his head was made of bone and it had a shape just like a horse's head, but he ran out to a point at his tail, and his head and his tail were all covered with bone. He lived in the Grand Lagoon at Pensacola in Florida, 239where the water is shallow and warm and there are lots of seaweeds. So he wound his tail around a stem of seaweed and hung with his head down, waiting to see what would happen next, and then he saw another little sea-horse hanging on another seaweed. And the other sea-horse put out a lot of little eggs, and the little eggs all lay on the bottom of the sea at the foot of the seaweed. So Hippocampus crawled down from the seaweed where he was and gathered up all those little eggs, and down on the under side of his tail where the skin is soft he made a long slit for a pocket, and then he stuffed all the eggs into this pocket and fastened it together and stuck it with some slime. So he had all the other sea-horse's eggs in his own pocket.

"Then he went up on the seawrack again and twisted his tail around it, and hung there with his head down to see what would happen next. The sun shone down on him, and by and by all the little eggs began to hatch out, and each one of the eggs was a little sea-pony, shaped just like a sea-horse. And when he hung there with his head down he could feel all the little sea-ponies squirming inside his pocket, and by and by they squirmed so much that they pushed the pocket open, and then every one crawled away from him, and he couldn't get them back, and so he went along with them and watched to see that nothing should hurt them. And by and by they hung themselves all up on the seaweeds, and they are hanging there yet. And so he crawled back to his own piece of seaweed and twisted his tail around it, and waited to see what would happen next. And what happened next was just the same thing over again."

Suborder Hypostomides, the Sea-moths: Pegasidæ.—The small suborder of Hypostomides (ὑπό, below; στόμα, mouth) consists of the family of Pegasidæ. These "sea-moths" are fantastic little fishes, probably allied to the sticklebacks, but wholly unique in form. The slender body is covered with bony plates, the gill-covers are reduced to a single plate. The small mouth underneath a long snout has no teeth. The preopercle and the symplectic are both wanting. The ventrals are abdominal, formed of two rays, and the very large pectoral fin is placed horizontally like a great wing.

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Fig 190.—Sea-moth, Zalises umitengu Jordan & Snyder. Misaki, Japan. (View from below.)

The species, few in number, known as sea-moths and sea-dragons, rarely exceed four inches in length. They are found in the East Indies and drift with the currents northward to Japan. The genera are Pegasus, Parapegasus, and Zalises. The best-known species are Zalises draconis and Pegasus volitans.

No fossil species of Pegasidæ are known.

Suborder Salmopercæ, the Trout-perches: Percopsidæ.—More ancient than the Hemibranchii, and still more distinctly in the line of transition from soft-rayed to spiny-rayed fishes, is the small suborder of Salmopercæ. This is characterized by the presence of the adipose fin of the salmon, in connection with the mouth, scales, and fin-spines of a perch. The premaxillary forms the entire edge of the upper jaw, the maxillary being without teeth. The air-bladder retains a rudimentary duct. The bones of the head are full of mucous cavities, as in the European perch called Gymnocephalus and Acerina. There are two spines in the dorsal and one or two in the anal, while the abdominal ventrals have each a spine and eight rays. Two species only are known among living fishes, these emphasizing more perfectly than any other known forms the close relation really existing between spinous and soft-rayed forms. The single family of Percopsidæ would seem to find its place in Cretaceous rocks rather than in the waters of to-day.

Fig. 191.—Sand-roller, Pecropsis guttatus Agassiz. Okoboji Lake, Ia.

242Percopsis guttata, the trout-perch or sand-roller of the Great Lakes, is a pale translucent fish with dark spots, reaching a length of six inches. It abounds in the Great Lakes and their tributaries and is occasionally found in the Delaware, Ohio, Kansas, and other rivers and northwestward as far as Medicine Hat on the Saskatchewan. It is easily taken with a hook from the piers at Chicago.

Fig. 192.—Oregon Trout-perch, Columbia transmontana Eigenmann. Umatilla River, Oregon.

Columbia transmontana is another little fish of similar type, but rougher and more distinctly perch-like. It is found in sandy or weedy lagoons throughout the lower basin of the Columbia, where it was first noticed by Dr. Eigenmann in 1892. From the point of view of structure and classification, this left-over form is one of the most remarkable of American fishes.

Fig. 193.—Erismatopterus endlicheri Cope. Green River Eocene. (After Cope.)

Erismatopteridæ.—Here should perhaps be placed the family of Erismatopteridæ, represented by Erismatopterus levatus and other species of the Green River Eocene shales. In Erismatopterus the 243short dorsal has two or three spines, there are two or three spines in the anal, and the abdominal ventrals are opposite the dorsal. Allied to Erismatopterus is Amphiplaga of the same deposits.

We cannot, however, feel sure that these extinct fragments, however well preserved, belonged to fishes having an adipose fin. Among spiny-rayed fishes the Percopsidæ alone retain this character, and the real affinities of Erismatopterus may be with Aphredoderidæ and other percoid forms.

The relations of the extinct family of Asineopidæ are also still uncertain. This group comprises fresh-water fishes said to be allied to the Aphredoderidæ, but with the pelvic bones not forked. Asineops pauciradiata, squamifrons and viridensis are described from the Green River shales. With Erismatopterus all these fishes may belong to the suborder of Salmopercæ, but, as above stated, the possession of the adipose fin, the most characteristic trait of the Salmopercæ, cannot be verified in the fossil remains.

Fig. 194.—Shoulder-girdle of the Opah, Lampris guttatus (Brünnich), showing the enlarged infraclavicle. (After Boulenger.)

Suborder Selenichthyes, the Opahs: Lamprididæ.—We may bring together as constituting another suborder certain forms of uncertain relationship, but which seem to be transitional between deep-bodied extinct Ganoids and the forms allied to Platax, Zeus, and Antigonia. The name of Selenichthyes (σηλήνη, moon; ἰχθύς, fish) is suggested by Boulenger for the group of opahs, or moonfishes. These are characterized by the highly compressed body, the great development of a large hypocoracoid, 244and especially by the structure of the ventral fins, which are composed of about fifteen rays instead of the one spine and five rays characteristic of the specialized perch-like fishes. The living forms of this type are further characterized by the partial or total absence of the spinous dorsal, by the small oblique mouth, and the prominence of the ventral curve of the body. A thorough study of the osteology of these forms living and fossil will be necessary before the group can be properly defined. The large bone above mentioned was at first considered by Boulenger as the interclavicle or infraclavicle, the hypocoracoid being regarded by him as displaced, lying with the actinosts. But it is certain, from the studies of Mr. Starks, that this bone is the real hypocoracoid, which in this case is simply exaggerated in size, but placed as in ordinary fishes.

The single living family, Lamprididæ, contains but one species, Lampris guttatus, known as opah, moonfish, mariposa, cravo, Jerusalem haddock, or San Pedro fish. This species reaches a length of six feet and a weight of 500 to 600 pounds. Fig. 199 (Vol. I) is taken from a photograph of an example weighing 317½ pounds taken near Honolulu by Mr. E. L. Berndt. The body is almost as deep as long, plump and smooth, without scales or bony plates. The vertebræ are forty-five in number, and the large ventrals contain about fifteen rays. The dorsal is without spines, the small mouth without teeth. The color is a "rich brocade of silver and lilac, rosy on the belly, everywhere with round silvery spots." The head and back have ultramarine tints, the jaws and fins are vermilion. On a drawing of this fish made at Sable Island in 1856, Mr. James Farquhar wrote (to Dr. J. Bernard Gilpin): "Just imagine the body, a beautiful silver interspersed with spots of a lighter color about the size of sixpence, the eyes very large and brilliant, with a golden ring around them. You will then have some idea of the splendid appearance of the fish when fresh. If Caligula had seen them I might have realized a fortune."

The skeleton of the opah is very firm and heavy. The flesh is of varying shades of salmon-red, tender, oily, and of a rich, exquisite flavor scarcely surpassed by any other fish whatsoever.

245The opah is a rare fish, swimming slowly near the surface and ranging very widely in all the warm seas. It was first noticed in Norway by Gunner, the good bishop of Throndhjem, about 1780. It was soon after recorded from Elsinore, Torbay, and Madeira, and is occasionally taken in various places in Europe. It is also recorded from Newfoundland, Sable Island, Cuba, Monterey, San Pedro Point (near San Francisco), Santa Catalina, Honolulu, and Japan.

The specimen studied by the writer came ashore at Monterey in an injured condition, having been worsted in a struggle with some better-armed fish.

Allied to Lampris is the imposing extinct species known as Semiophorus velifer from the Eocene of Monte Bolca near Verona, the type of the extinct family of Semiophoridæ. This is a deep compressed fish, with very high spinous dorsal and very long, many-rayed ventrals. Other related species are known also from the Eocene. There is no evidence of any close relation between these fishes with Caranx or Platax, with which Woodward associates Semiophorus.

The Semiophoridæ differ from the Lamprididæ chiefly in the development of the spinous dorsal fin, which is composed of many slender rays.

Suborder Zeoidea.—Not far from the Selenichthyes and the Berycoidei we may place the singular group of John Dories, or zeoid fishes. These have the ventral fins thoracic and many-rayed, the dorsal fin provided with spines, and the post-temporal, as in the Chætodontidæ, fused with the skull. Dr. Boulenger calls attention to the close relation of these fishes to the flounders, and suggests the possible derivation of both from a synthetic type, the Amphistiidæ, found in the European Eocene. The Amphistiidæ, Zeidæ, and flounders are united by him to form the group or suborder Zeorhombi, characterized by the thoracic ventrals, which have the rays not I, 5 in number, by the progressive degeneration of the fin-spines and the progressive twisting of the cranium, bringing the two eyes to the same side of the head. It is not certain that the flounders are really derived from Zeus-like fishes, but no other guess as to their origin has more elements of probability.

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Fig. 195.—Semiophorus velifer Volta. Eocene. (After Agassiz, per Zittel.)

247We may, however, regard the Zeoidea on the one hand and the Heterosomata on the other as distinct suborders. This is certain, that the flounders are descended from spiny-rayed forms and that they have no affinities with the codfishes.

Fig. 196.—Amphistium paradoxum Agassiz. Upper Eocene. (Supposed ancestor of the flounders). (After Boulenger.)

Amphistiidæ.—The Amphistiidæ, now extinct, are deep-bodied, compressed fishes, with long, continuous dorsal and anal fins in which a few of the anterior rays are simple, slender spines scarcely differentiated from the soft rays. The form of body and the structure of the fins are essentially as in the flounders, from which they differ chiefly by the symmetry of the head, the eyes being normally placed. Amphistium paradoxum is described by Agassiz from the upper Eocene. It occurs in Italy and France. In its dorsal and anal fins there are about twenty-two rays, the first three or four undivided. The teeth are minute or absent and there is a high supraoccipital crest.

The John Dories: Zeidæ.—The singular family of Zeidæ, or John Dories, agrees with Chætodonts in the single character of the fusion of the post-temporal with the skull. The species, however, diverge widely in other regards, and their ventral fins are essentially those of the Berycoids. In all the species there are seven to nine soft rays in the ventral fins, as in the Berycoid fishes. Probably the character of the fused post-temporal has been independently derived. The anterior vertebræ in Zeus, as in Chætodon, are closely crowded together. In the Zeidæ the spinous dorsal is well developed, the body naked or with very thin scales, and provided with bony warts at least around the bases of dorsal and anal fins. The species are mostly of small size, silvery in color, living in moderate depths in warm seas. The best-known genus is Zeus, which is a group of shore-fishes of the waters of Asia and Europe. The common John Dory (called in Germany Härings-König, or king of the herrings), Zeus faber, abounds in shallow bays on the coasts of Europe. It reaches a length of nearly a foot, and is a striking feature of the markets of southern Europe. The dorsal spines are high, the mouth large, and on the sides is a black ring, said by some to be the mark of the thumb of St. Peter, who is reported to have taken a coin from the mouth of this species. A black spot on several other species is associated with the same legend.

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Fig. 197.—The John Dory, Zeus faber. Linnæus. Devon, England.

249On the coasts of Japan abounds the Matao, or target-fish (Zeus japonicus), very similar to the European species and like it in form and color. Zenopsis nebulosa and Zen itea also occur on the coasts of Japan. The remaining Zeidæ (Cyttus, Zenopsis, Zenion, etc.) are all rare species occasionally dredged especially in the Australian region. Zeus priscus is recorded from the Tertiary, and Cyttoides glaronensis from the upper Eocene of Glavus.

Grammicolepidæ.—The Grammicolepidæ, represented by a single species, Grammicolepis brachiusculus, rarely taken off the coast of Cuba, is related to the Zeidæ. It has rough, ridged, parchment-like scales deeper than long. The ventrals are thoracic, with the rays in increased number, as in Zeus and Beryx, with each of which it suggests affinity.

The Berycoid Fishes.—We may place in a separate order a group of fishes, mostly spiny-rayed, which appeared earlier in geological time than any other of the spinous forms, and which in several ways represent the transition from the isospondylous fishes to those of the type of the mackerel and perch. In the berycoid fishes the ventral fins are always thoracic, the number of rays almost always greater than I, 5, and in all cases an orbitosphenoid bone is developed in connection with the septum between the orbits above. This bone is found in the Isospondyli and other primitive fishes, but according to the investigations of Mr. E. C. Starks it is wanting in all percoid and scombroid forms, as well as in the Haplomi and in all the higher fishes. This trait may therefore, among thoracic fishes, be held to define the section or suborder of Berycoidei.

Fig. 198.—Skull of a Berycoid fish, Beryx splendens Cuv. & Val., showing the orbitosphenoid (OS), characteristic of all Berycoid fishes.

These fishes, most primitive of the thoracic types, were more abundant in Cretaceous and Eocene times than now. The possession of an increased number of soft rays in the ventral fins is archaic, although in one family, the Monocentridæ, the number is reduced to three. Most of the living Berycoidei retain through life the archaic duct to the air-bladder characteristic of most abdominal or soft-rayed fishes. In some however, the duct is lost. For the first time in the fish series the number of twenty-four vertebræ appears. In most spiny-rayed 251fishes of the tropics, of whatever family, this number is retained.

In every case spines are present in the dorsal fin, and in certain cases the development of the spinous dorsal surpasses that of the most extreme perch-like forms. In geological times the Berycoids preceded all other perch-like fishes. They are probably ancestral to all the latter. All the recent species, in spite of high specialization, retain some archaic characters.

The Alfonsinos: Berycidæ.—The typical family, Berycidæ, is composed of fishes of rather deep water, bright scarlet or black in color, with the body short and compressed, the scales varying in the different genera. The single dorsal fin has a few spines in front, and there are no barbels. The suborbitals are not greatly developed.

Fig. 199.—Beryx splendens Lowe. Gulf Stream.

The species of Beryx, called in Spanish Alfonsino, Beryx elegans and Beryx decadactylus, are widely distributed at moderate depths, the same species being recorded from Portugal, Madeira, Cuba, the Gulf Stream, and Japan. The colors are very handsome, being scarlet with streaks of white or golden. These fishes reach the length of a foot or more and are valued as food where sufficiently common.

Numerous species of Beryx and closely allied genera are found in all rocks since Cretaceous times; Beryx dalmaticus, from the Cretaceous of Dalmatia, is perhaps the earliest. Beryx insculptus is found in New Jersey, but no other Berycoids 252are yet known as fossils from North America. Sphenocephalus, with four anal spines, is found in the chalk, as are also species of Acrogaster and Pycnosterinx, these being the earliest of fishes with distinctly spiny fins.

Fig. 200.—Hoplopteryx lewesiensis (Mantell), restored. English Cretaceous Family Berycidæ. (After Woodward.)

The Trachichthyidæ are deep-sea fishes with short bodies, cavernous skulls, and rough scales. The dorsal is short, with a few spines in front. The suborbitals are very broad, often covering the cheeks, and the anal fin is shorter than the dorsal, a character which separates these fishes from the Berycidæ, in which group the anal fin is very long. The belly has often a serrated edge, and the coloration is red or black, the black species being softer in body and living in deeper water. Species of Hoplostethus, notably Hoplostethus mediterraneus, are found in most seas at a considerable depth. Trachichthys, a genus scarcely distinguishable from Hoplostethus, is found in various seas. The genus Paratrachichthys is remarkable for the anterior position of the vent, much as in Aphredoderus. Species occur in Japan and Australia. Gephyroberyx, with the dorsal fin notched, is known from Japan (G. japonicus) and Madeira (G. darwini).

We may also refer to the Trachichthyidæ certain species of still deeper waters, black in color and still softer in texture, with smaller scales which are often peculiar in form. These constitute the genera Caulolepis, Anoplogaster, Melamphaës, 253and Plectromus. In Caulolepis the jaws are armed with very strong canines.

Allied to the Trachichthyidæ are also the fossil genera Hoplopteryx and Homonotus. Hoplopteryx lewesiensis, from the English chalk, is one of the earliest of the spiny-rayed fishes.

Fig. 201.—Paratrachichthys prosthemius Jordan & Fowler, Misaki, Japan. Family Trachichthyidæ.

The Soldier-fishes: Holocentridæ.—The soldier-fishes (Holocentridæ), also known as squirrel-fishes, Welshmen, soldados, matajuelos, malau, alehi, etc., are shore fishes very characteristic of rocky banks in the tropical seas. In this family the flesh is firm and the large scales very hard and with very rough edges. There are eleven spines in the dorsal and four in the anal, the third being usually very long. The ventral fins have one spine and seven soft rays. The whole head and body are rough with prickles. The coloration is always brilliant, the ground hue being scarlet or crimson, often with lines or stripes of white, black, or golden. The fishes are valued as food, and they furnish a large part of the beauty of coloration so characteristic of the fishes of the coral reefs. The species are active, pugnacious, carnivorous, but not especially voracious, the mouth being usually small.

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Fig. 202.—Soldier-fish, Holocentrus ascenscionis (Osbeck).

Fig. 203.—Soldier-fish, Holocentrus ittodai Jordan & Fowler. Riu Kiu Islands, Japan.

The genus Holocentrus is characterized by the presence of a large spine on the angle of the preopercle. Its species are especially numerous, Holocentrus ascenscionis, abundant in Cuba, ranges northward in the Gulf Stream. Holocentrus suborbitalis, the mojarra cardenal, is a small, relatively dull species swarming about the rocks of western Mexico. Holocentrus spinosissimus is a characteristic fish of Japan. Many other species abound throughout Polynesia and the East Indies, as well as in tropical America. Holocentrus ruber and Holocentrus 255diadema are common species of Polynesia and the East Indies. Other abundant species are H. spinifer, H. microstomus, and H. violascens.

Holocentrus marianus is the marian of the French West Indies. Holocentrus sammara, and related large-mouthed species occur in Polynesia.

Fig. 204.—Ostichthys japonicus (Cuv. & Val.). Giran, Formosa.

In Myripristis the preopercular spine is wanting and the air-bladder is divided into two parts, the anterior extending to the ear. Myripristis jacobus is the brilliantly colored candil, or "Frère Jacques," of the West Indies. Species of Myripristis are known in Hawaii as u-u. A curious method of catching Myripristis murdjan is pursued on the Island of Hawaii. A living fish is suspended by a cord in front of a reef inhabited by this species. It remains with scarlet fins spread and glistening red scales. Its presence is a challenge to other individuals, who rush out to attack it. These are then drawn out by a concealed scoop-net, and a fresh specimen is taken as a decoy. Myripristis pralinius, M. multiradiatus, and other species occur in Polynesia. Ostichthys is allied to Myripristis but with very large rough scales. Ostichthys japonicus is a large and showy fish of the waters of Japan. Ostichthys pillwaxi 256occurs at Honolulu. Holotrachys lima is a small, brick-red fish with small very rough scales found throughout Polynesia.

Fossil species of Holocentrus, Myripristis, and related extinct genera occur in the Eocene and Miocene. Holocentrus macrocephalus, from Monte Bolca Eocene, is one of the best known. Myricanthus leptacanthus from the same region, has very slender spines in the fins.

Fig. 205.—Pine-cone Fish, Monocentris japonicus (Houttuyn). Waka, Japan.

The Polymixiidæ.—The family of Polymixiidæ, or barbudos, is one of the most interesting in Ichthyology from its bewildering combination of characters belonging to different groups. With the general aspect of a Berycoid, the ventral rays I, 7, and the single dorsal fin with a few spines, Polymixia has the scales rather smooth and at the chin are two long barbels which look remarkably like those of the family of Mullidæ or Surmullets. As in the Mullidæ, there are but four branchiostegals. In other regards the two groups seem to have little in common. According to Starks, the specialized feelers at the chin are different in structure and must have been independently developed in the two groups. In Polymixia, each barbel is suspended from the hypohyal; three rudimentary branchiostegals forming its thickened base. In Mullus, each barbel is suspended from the trip of a slender projection of the ceratohyal, having no connection with the branchiostegals. Polymixia possesses 257the orbitosphenoid bone and is a true berycoid, while the Mullidæ are genuine percoid fishes.

Four species of Polymixia are recorded from rather deep water: Polymixia nobilis from Madeira, Polymixia lowei from the West Indies, Polymixia berndti from Hawaii, and Polymixia japonica from Japan. All are plainly colored, without red.

The Pine-cone Fishes: Monocentridæ.—Among the most extraordinary of all fishes is the little family of Monocentridæ, or pine-cone fishes. Monocentris japonicus, the best-known species, is common on the coasts of Japan. It reaches the length of five inches. The body is covered with a coat of mail, made of rough plates which look as though carelessly put together. The dorsal spines are very strong, and each ventral fin is replaced by a very strong rough spine. The animal fully justifies the remark of its discoverer, Houttuyn (1782), that it is "the most remarkable fish which exists." It is dull golden brown in color, and in movement as sluggish as a trunkfish. A similar species, called knightfish, Monocentris gloriæ-maris, is found in Australia. No fossils allied to Monocentris are known.

Suborder Percomorphi, the Mackerels and Perches.—We may place in a single suborder the various groups of fishes which cluster about the perches, and the mackerels. The group is not easily definable and may contain heterogeneous elements. We may, however, arrange in it, for our present purposes, those spiny-rayed fishes having the ventral fins thoracic, of one spine and five rays (the ventral fin occasionally wanting or defective, having a reduced number of rays), the lower pharyngeal bones separate, the suborbital chain without backward extension or bony stay, the post-temporal normally developed and separate from the cranium, the premaxillary and maxillary distinct, the cranium itself without orbitosphenoid bone, having a structure not greatly unlike that of perch or mackerel, and the back-bone primitively of twenty-four vertebræ, the number increased in arctic, pelagic, or fresh-water offshoots.

The species, comprising the great body of the spiny-rayed forms, group themselves chiefly about two central families, the Scombridæ, or mackerels, and the Serranidæ, the sea-bass, with their fresh-water allies, the Percidæ, or perch.

The Mackerel Tribe: Scombroidea.—The two groups of Percomorphi, the mackerel-like and the perch-like, admit of no exact definition, as the one fully grades into the other. The mackerel-like forms, or Scombroidea, as a whole are defined by their adaptation for swift movement. The profile is sharp anteriorly, the tail slender, with widely forked caudal; the scales are usually small, thin, and smooth, of such a character as not to produce friction in the water.

In general the external surface is smooth, the skeleton light and strong, the muscles firm, and the species are carnivorous 259and predaceous. But among the multitude of forms are many variations, and some of these will seem to be exceptions to any definition of mackerel-like fishes which could possibly be framed.

The mackerels, or Scombroidea, have usually the tail very slender, composed of very strong bones, with widely forked fin. In the perch and bass the tail is stout, composed largely of flesh, the supporting vertebræ relatively small and spread out fan-fashion behind. Neither mackerels nor perch nor any of their near allies ever have more than five soft rays in the ventral fins, and the persistence of this number throughout the Percomorphi, Squamipinnes, Pharyngognathi, and spiny fishes generally must be attributed to inheritance from the primitive perch-like or mackerel-like forms. In almost all the groups to be considered in this work, after the Berycoidea the ventral rays are I, 5, or else fewer through degeneration, never more. In the central or primitive members of most of these groups there are twenty-four vertebræ, the number increased in certain forms, probably through repetitive degeneration.