CHAPTER XXI

LABYRINTHICI AND HOLCONOTI

=THE Labyrinthine Fishes.=—An offshoot of the _Percomorphi_ is the group of _Labyrinthici_, composed of perch-like fishes which have a very peculiar structure to the pharyngeal bones and respiratory apparatus. This feature is thus described by Dr. Gill:

"The upper elements of one of the pairs of gill-bearing arches are peculiarly modified. The elements in question (called branchihyal) of each side, instead of being straight and solid, as in most fishes, are excessively developed and provided with several thin plates or folds, erect from the surface of the bones and the roof of the skull, to which the bones are attached. These plates, by their intersection, form chambers, and are lined with a vascular membrane, which is supplied with large blood-vessels. It was formerly supposed that the chambers referred to had the office of receiving and retaining supplies of water which should trickle down and keep the gills moist; such was supposed to be an adaptation for the sustentation of life out of the water. The experiments of Surgeon Day, however, throw doubt upon this alleged function, and tend to show: (1) that these fishes died when deprived of access to atmospheric air, not from any deleterious properties either in the water or in the apparatus used, but from being unable to subsist on air obtained solely from the water, aerial respiration being indispensable; (2) that they can live in moisture out of the water for lengthened periods, and for a short, but variable period in water only; and (3) that the cavity or receptacle does not contain water, but has a moist secreting surface, in which air is retained for the purpose of respiration. It seems probable that the air, after having been supplied for aerial respiration, is ejected by the mouth, and not swallowed to be discharged per anum. In fine, the two respiratory factors of the branchial apparatus have independent functions: (1) the labyrinthiform, or branchihyal portion, being a special modification for the respiration of atmospheric air, and (2) the gill filaments discharging their normal function. If, however, the fish is kept in water and prevented from coming to the surface to swallow the atmospheric air, the labyrinthiform apparatus becomes filled with water which cannot be discharged, owing to its almost non-contractile powers. There is thus no means of emptying it, and the water probably becomes carbonized and unfit for oxygenizing the blood, so that the whole of the respiration is thus thrown on the branchiæ. This will account for the fact that when the fish is in a state of quiescence, it lives much longer than when excited, whilst the sluggishness sometimes evinced may be due to poisoned or carbonized blood."

Four families of labyrinth-gilled fishes are recognized by Professor Gill; and to these we may append a fifth, which, however, lacks the elaborate structures mentioned above and which shows other evidences of degeneration.

=The Climbing-perches: Anabantidæ.=—The family of _Anabantidæ_, according to Gill, "includes those species which have the mouth of moderate size and teeth on the palate (either on the vomer alone, or on both the vomer and palatine bones). To the family belongs the celebrated climbing-fish.

"The climbing-fish (_Anabas scandens_) is especially noteworthy for the movability of the suboperculum. The operculum is serrated. The color is reddish olive, with a blackish spot at the base of the caudal fin; the head, below the level of the eye, grayish, but relieved by an olive band running from the angle of the mouth to the angle of the preoperculum, and with a black spot on the membrane behind the hindermost spines of the operculum.

"The climbing-fish was first made known in a memoir, printed in 1797, by Daldorf, a lieutenant in the service of the Danish East India Company at Tranquebar. Daldorf called it _Perca scandens_, and affirmed that he himself had taken one of these fishes, clinging by the spine of its operculum in a slit in the bark of a palm (_Borassus flabelliformis_) which grew near a pond. He also described its mode of progression; and his observations were substantially repeated by the Rev. Mr. John, a missionary resident in the same country. His positive evidence was, however, called into question by those who doubted on account of hypothetical considerations. Even in popular works not generally prone to even a judicious skepticism, the accounts were stigmatized as unworthy of belief. We have, however, in answer to such doubts, too specific information to longer distrust the reliability of the previous reports.

"Mr. Rungasawmy Moodeliar, a native assistant of Capt. Jesse Mitchell of the Madras Government Central Museum, communicated to his superior the statement that 'this fish inhabits tanks or pools of water, and is called _Panai feri_, i.e., the fish that climbs palmyra-trees. When there are palmyra-trees growing by the side of a tank or pool, when heavy rain falls and the water runs profusely down their trunks, this fish, by means of its opercula, which move unlike those of other fishes, crawls up the tree sideways (i.e., inclining to the sides considerably from the vertical) to a height of from five to seven feet, and then drops down. Should this fish be thrown upon the ground, it runs or proceeds rapidly along in the same manner (sideways) as long as the mucus on it remains.'

"These movements are effected by the opercula, which, it will be remembered, are unusually mobile in this species; they can, according to Captain Mitchell (and I have verified the statement), be raised or turned outwards to nearly a right angle with the body, and when in that position, the suboperculum distends a little, and it appears that it is chiefly by the spines of this latter piece that the fish takes a purchase on the tree or ground. 'I have,' says Captain Mitchell, 'ascertained by experiment that the mere closing of the operculum, when the spines are in contact with any surface, even common glass, pulls an ordinary-sized fish forwards about half an inch,' but it is probable that additional force is supplied by the caudal and anal fins, both of which, it is said, are put in use when climbing or advancing on the ground; the motion, in fact, is described as a wriggling one.

"The climbing-fish seems to manifest an inclination to ascend streams against the current, and we can now understand how, during rain, the water will flow down the trunk of a tree, and the climbing-fish, taking advantage of this, will ascend against the down-flow by means of the mechanism already described, and by which it is enabled to reach a considerable distance up the trunk." (Gill.)

=The Gouramis: Osphromenidæ.=—"The _Osphromenidæ_ are fishes with a mouth of small size, and destitute of teeth on the palate. To this family belongs the gourami, whose praises have been so often sung, and which has been the subject of many efforts for acclimatization in France and elsewhere by the French.

"The gourami (_Osphromenus goramy_) has an oblong, oval form, and, when mature, the color is nearly uniform, but in the young there are black bands across the body, and also a blackish spot at the base of the pectoral fin. The gourami, if we can credit reports, occasionally reaches a gigantic size, for it is claimed that it sometimes attains a length of 6 feet, and weighs 150 pounds, but if this is true, the size is at least exceptional, and one of 20 pounds is a very large fish; indeed, they are considered very large if they weigh as much as 12 or 14 pounds, in which case they measure about 2 feet in length.

"The countries in which the gourami is most at home lie in the intertropical belt. The fish is assiduous in the care of its young, and prepares a nest for the reception of eggs. The bottom selected is muddy, the depth variable within a narrow area, that is, in one place about a yard, and near by several yards deep.

"They prefer to use, for the nests, tufts of a peculiar grass (_Panicum jumentorum_) which grows on the surface of the water, and whose floating roots, rising and falling with the movements of the water, form natural galleries, under which the fish can conceal themselves. In one of the corners of the pond, among the plants which grow there, the gouramis attach their nest, which is of a nearly spherical form, and composed of plants and mud, and considerably resembles in form those of some birds.

"The gourami is omnivorous, taking at times flesh, fish, frogs, insects, worms, and many kinds of vegetables; and on account of its omnivorous habit, it has been called by the French colonists of Mauritius _porc des rivières_, or 'water-pig.' It is, however, essentially a vegetarian, and its adaptation for this diet is indicated by the extremely elongated intestinal canal, which is many times folded upon itself. It is said to be especially fond of the leaves of several araceous plants. Its flesh is, according to several authors, of a light-yellow straw-color, firm and easy of digestion. They vary in quality with the nature of the waters inhabited, those taken from a rocky river being much superior to those from muddy ponds; but those dwelling at the mouth of rivers, where the water is to some extent brackish, are the best of all. Again, they vary with age; and the large, overgrown fishes are much less esteemed than the small ones. They are in their prime when three years old. Dr. Vinson says the flavor is somewhat like that of carp; and, if this is so, we may entertain some skepticism as to its superiority; but the unanimous testimony in favor of its excellence naturally leads to the belief that the comparison is unfair to the gourami.

"Numerous attempts have been made by the French to introduce the gourami into their country, as well as into several of their provinces; and for a number of years consignments of the eggs, or the young, or adult fish, were made. Although at least partially successful, the fish has never been domiciliated in the Republic, and, indeed, it could not be reasonably expected that it would be, knowing, as we do, its sensitiveness to cold and the climates under which it thrives.

"The fish of paradise (_Macropodus viridi-auratus_) is a species remarkable for its beauty and the extension of its fins, and especially of the ventrals, which has obtained for it the generic name _Macropodus_. To some extent this species has also been made the subject of fish-culture, but with reference to its beauty and exhibition in aquaria and ponds, like the goldfish, rather than for its food qualities.

"The only other fish of the family that needs mention is the fighting-fish (_Betta pugnax_). It is cultivated by the natives of Siam, and a special race seems to have been the result of such cultivation. The fishes are kept in glasses of water and fed, among other things, with the larvæ of mosquitoes or other aquatic insects. 'The Siamese are as infatuated with the combats of these fishes as the Malays are with their cock-fights, and stake on the issue considerable sums, and sometimes their own persons and families. The license to exhibit fish-fights is farmed, and brings a considerable annual revenue to the king of Siam. The species abounds in the rivulets at the foot of the hills of Penang. The inhabitants name it 'pla-kat,' or the 'fighting-fish.'"

The _Helostomidæ_ are herbivorous, with movable teeth on the lips and with long intestines. _Helostoma temmincki_ lives in the rivers of Java, Borneo, and Sumatra.

The _Luciocephalidæ_ of East Indian rivers have the suprabranchial organ small, formed of two gill-arches dilated by a membrane. In these species there are no spines in the dorsal and anal, while in the _Anabantidæ_ and _Osphromenidæ_ numerous spines are developed both in the dorsal and anal. _Luciocephalus pulcher_ indicates a transition toward the _Ophicephalidæ_.

=The Snake-head Mullets: Ophicephalidæ.=—The family of _Ophicephalidæ_, snake-head mullets, or China-fishes, placed among the _Percesoces_ by Cope and Boulenger, seems to us nearer the Labyrinthine fishes, of which it is perhaps a degenerate descendant. The body is long, cylindrical, covered with firm scales which on the head are often larger and shield-like. The mouth is large, the head pike-like, and the habit carnivorous and voracious. There are no spines in any of the fins, but the thoracic position of the ventrals indicates affinity with perch-like forms and the absence of ventral spines seems rather a feature of degradation, the more so as in one genus (_Channa_) the ventrals are wanting altogether. The numerous species are found in the rivers of southern China and India, crossing to Formosa and to Africa. They are extremely tenacious of life, and are carried alive by the Chinese to San Francisco and to Hawaii, where they are now naturalized, being known as "China-fishes."

These fishes have no special organ for holding water on the gills, but the gill space may be partly closed by a membrane. According to Dr. Günther, these fishes are "able to survive drought living in semi-fluid mud or lying in a torpid state below the hard-baked crusts of the bottom of a tank from which every drop of water has disappeared. Respiration is probably entirely suspended during the state of torpidity, but whilst the mud is still soft enough to allow them to come to the surface, they rise at intervals to take in a quantity of air, by means of which their blood is oxygenized. This habit has been observed in some species to continue also to the period of the year in which the fish lives in normal water, and individuals which are kept in a basin and prevented from coming to the surface and renewing the air for respiratory purposes are suffocated. The particular manner in which the accessory branchial cavity participates in respiratory functions is not known. It is a simple cavity, without an accessory branchial organ, the opening of which is partly closed by a fold of the mucous membrane."

_Ophicephalus striatus_ is the most widely diffused species in China, India, and the Philippines, living in grassy swamps and biting at any bait from a live frog to an artificial salmon-fly. It has been introduced into Hawaii. _Ophicephalus marulius_ is another very common species, as is also _Channa orientalis_, known by the absence of ventral fins.

=Suborder Holconoti, the Surf-fishes.=—Another offshoot from the perch-like forms is the small suborder of _Holconoti_ (ὅλκος, furrow; νῶτος, back). It contains fishes percoid in appearance, with much in common with the _Gerridæ_ and _Sparidæ_, but with certain striking characteristics not possessed by any perch or bass. All the species are viviparous, bringing forth their young alive, these being in small number and born at an advanced stage of development. The lower pharyngeals are solidly united, as in the _Labridæ_, a group which these fishes resemble in scarcely any other respects. The soft dorsal and anal are formed of many fine rays, the anal being peculiarly modified in the male sex. The nostrils, ventral fins, and shoulder-girdle have the structure normal among perch-like fishes, and the dorsal furrow, which suggested to Agassiz the name of _Holconoti_, is also found among various perch-like forms.

=The Embiotocidæ.=—The group contains a single family, the _Embiotocidæ_, or surf-fishes. All but two of the species are confined to California, these two living in Japan. The species are relatively small fishes, from five inches to eighteen inches in length, with rather large, usually silvery scales, small mouths and small teeth. They feed mainly on crustaceans, two or three species being herbivorous. With two exceptions, they inhabit the shallow waters on sandy beaches, where they bring forth their young. They can be readily taken in nets in the surf. As food-fishes they are rather inferior, the flesh being somewhat watery and with little flavor. Many are dried by the Chinese. The two exceptions in distribution are _Hysterocarpus traski_, which lives exclusively in fresh waters, being confined to the lowlands of the Sacramento Basin, and _Zalembius rosaceus_, which descends to considerable depths in the sea. In _Hysterocarpus_ the spinous dorsal is very greatly developed, seventeen stout spines being present, the others having but eight to eleven and these very slender.

The details of structure vary greatly among the different species, for which reason almost every species has been properly made the type of a distinct genus. The two species found in Japan are _Ditrema temmincki_ and _Neoditrema ransonneti_. In the latter species the female is always toothless. Close to _Ditrema_ is the blue surf-fish of California, _Embiotoca jacksoni_, the first discovered and perhaps the commonest species. _Tæniotoca lateralis_ is remarkable for its bright coloration, greenish, with orange stripes. _Hypsurus caryi_, still brighter in color, orange, green and black, has the abdominal region very long. _Phanerodon furcatus_ and _P. atripes_ are dull silvery in color, as in _Damalichthys argyrosomus_, the white surf-fish, which ranges northward to Vancouver Island, and is remarkable for the extraordinary size of its lower pharyngeals. _Holconotus rhodoterus_ is a large, rosy species, and _Amphistichus argenteus_ a large species with dull yellowish cross-bands. _Rhachochilus toxotes_ is the largest species in the family and the one most valued as food. It is notable for its thick, drooping, ragged lips. _Hyperprosopon arcuatus_, the wall-eye surf-fish, is brilliantly silvery, with very large eyes. _H. agassizi_ closely resembles it, as does also the dwarf species, _Hypocritichthys analis_, to which the Japanese _Neoditrema ransonneti_ is very nearly related. The other species are all small. _Abeona minima_ and _A. aurora_ feed on seaweed. _Brachyistius frenatus_ is the smallest of all, orange-red in color, while its relative, _Zalembius rosaceus_, is handsomest of all, rose-red with a black lateral spot. _Cymatogaster aggregatus_, the surf-shiner, is a little fish, excessively common along the California coast, and from its abundance it has been selected by Dr. Eigenmann as the basis of his studies of these fishes. In this species the male shows golden and black markings, which are wanting in the silvery female, and the anterior rays of the anal are thickened or otherwise modified.

No fossil embiotocoids are recorded.

The viviparity of the Embiotocidæ was first made known by Dr. A. C. Jackson in 1863 in a letter to Professor Agassiz. From this letter we make the following extracts:

"A few days, perhaps a week, after the four trials, and on the _7th of June_, I rose early in the morning for the purpose of taking a mess of fish for breakfast, pulled to the usual place, baited with crabs, and commenced fishing, the wind blowing too strong for profitable angling; nevertheless on the first and second casts I fastened the two fishes, male and female, that I write about, and such were their liveliness and strength that they endangered my slight trout rod. I, however, succeeded in bagging both, though in half an hour's subsequent work I got not even a nibble from either this or any other species of fish. I determined to change the bait, to put upon my hook a portion of the fish already caught, and cut for that purpose into the larger of the two fish caught. I intended to take a piece from the thin part of the belly, when what was my surprise to see coming from the opening thus made _a small live fish_. This I at first supposed to be prey which this fish had swallowed, but on further opening the fish I was vastly astonished to find next to the back of the fish and slightly attached to it _a long very light violet bag, so clear and so transparent that I could already distinguish through it the shape, color, and formation of a multitude_ of small fish (_all facsimiles of each other_), with which it was well filled. I took it on board (we were occupying a small vessel which we had purchased for surveying purposes). When I opened the bag, I took therefrom _eighteen_ more of the young fish, precisely like in size, shape, and color the first I had accidentally extracted. The _mother was very large round her center and of a very dark-brown color, approaching about the back and on the fins a black color, and a remarkably vigorous fish_. The young which I took from her were in shape, save as to rotundity, perfect miniatures of the mother, formed like her, and of the same general proportions, except that the old one was (probably owing to her pregnancy) much broader and wider between the top of the dorsal and the ventral fins in proportion to her length than the young were. _As to color, they were in all respects like the mother, though the shades were many degrees lighter._ Indeed, they were in all respects like their mother and like each other, the same peculiar mouth, the same position and shape of the fins, and the same eyes and gills, and there cannot remain in the mind of any one who sees the fish in the same state that I did a single doubt that these young were the offspring of the fish from whose body I took them, and _that this species of fish gives birth to her young alive and perfectly formed, and adapted to seeking its own livelihood in the water. The number of young in the bag was nineteen_ (I fear I misstated the number in my former letter), _and every one as brisk and lively and as much at home in a bucket of salt water as if they had been for months accustomed to the water_. The male fish that was caught was not quite as large as the female, either in length or circumference, and altogether a more slim fish. I think we may reasonably expect to receive the specimens by the first of December. But I can hardly hope to get satisfactory specimens of the fish as I found it, with young well grown, before the return of the same season, viz., June. By that time I trust the facts will be fully decided, and the results, as important as they may be, fully appreciated."

Dr. Jackson's specimens came from Sausalito Bay, near San Francisco. Soon after the publication of this letter a similar discovery was made independently by Dr. William P. Gibbons, of Alameda. Still other specimens were made known in 1854 by Dr. Charles Girard, these having been collected in connection with the United States Pacific Railroad Surveys. The species first examined by Dr. Jackson was named by Agassiz _Embiotoca jacksoni_.

In Professor Agassiz's comments on Dr. Jackson's discovery he makes the following observations (_Amer. Jour. Science and Arts_, 1854):

"The female genital apparatus in the state of pregnancy consists of a large bag the appearance of which in the living animal has been described by Mr. Jackson. Upon the surface of it large vascular ramifications are seen, and it is subdivided internally into a number of distinct pouches, opening by wide slits into the lower part of the sac. This sac seems to be nothing but the widened lower end of the ovary, and the pouches within it to be formed by the folds of the ovary itself. In each of these pouches a young is wrapped up as in a sheet, and all are packed in the most economical manner as far as saving space is concerned, some having their head turned forwards and others backwards. _This is, therefore, a normal ovarian gestation._ The external genital opening is situated behind the anus, upon the summit and in the center of a conical protuberance formed by a powerful sphincter, kept in its place by two strong transverse muscles attached to the abdominal walls. The number of young contained in this sac seems to vary. Mr. Jackson counted nineteen; I have seen only eight or nine in the specimens sent by Mr. Cary, but since these were open when received it is possible that some had been taken out. However, their size is most remarkable in proportion to the mother. In a specimen of _Emb. jacksoni_ 10½ inches long and 4½ high the young were nearly 3 inches long and 1 inch high; and in an _Emb. caryi_ 8 inches long and 3¼ high the young were 2¾ inches long and ⅞ of an inch high. Judging from their size, I suspected for some time that the young could move in and out of this sac like young opossums, but on carefully examining the position of the young in the pouches, and also the contracted condition of the sphincter at the external orifice of the sexual organs, I remained satisfied that this could not be the case, and that the young which Mr. Jackson found so lively after putting them in a bucket of salt water had then for the first time come into free contact with the element in which they were soon to live; but at the same time it can hardly be doubted that the water penetrates into the marsupial sac, since these young have fully developed gills. The size of the young compared with that of the mother is very remarkable, being full one-third its length in the one, and nearly so in the other species. Indeed these young Embiotocæ, not yet hatched, are three or four times larger than the young of a Pomotis (of the same size) a full year old. In this respect these fishes differ from all the other viviparous species known to us. There is another feature about them of considerable interest, that while the two adults differ markedly in coloration, the young have the same dress, light yellowish olive with deeper and brighter transverse bands, something like the young trout and salmon in their parr dress."