The lower orders of teleosts retain many characteristics of the Holostei, and several of their families are known only as fossils in the Cretaceous and Tertiary rocks. The most primitive survivor of these ancient forms is the great tarpon of Florida and southward, another species of which occurs in India—such wide differences in habitats being an evidence of antiquity in nearly all cases among animals. The extraordinary mormoids of northern Africa, and the eellike gymnarchus of Gambia, are other relics of the past, as also are several other queer African families, the barramundi of Australia, and the arapaima of the Amazon region. The one last named is the largest fresh-water fish known, specimens exceeding fifteen feet in length, and weighing 400 pounds, all of which is excellent food. The mother protects her offspring which, when young, swim in front of her. Several of these old-fashioned teleosts, like our bowfin and the primitive Dipneusti, make elaborate nests in which their eggs are deposited, and they and the fry are carefully guarded by the parent. In this same suborder come the most familiar and useful game and food fishes—the shad, herring, trout, salmon, whitefish, smelt, etc.

The shad family is a very large one, numbering about 200 species, most of which are marine, but a few are "anadromous," that is, they ascend rivers of fresh water to spawn in the shallows near their sources. This is the habit of American shad, of which there is only one species in spite of the many local names in use; and it is regarded by the fisheries authorities as the most valuable river fish in the country except the Chinook salmon; but the supply of it would have been exhausted long ago had it not been for the incessant and energetic methods of replanting of fry, artificially bred, in all the eastern rivers, and the transplanting of them to rivers on the Pacific Coast, the credit for which valuable public service belongs to the United States Bureau of Fisheries.

The shad is to be found from Florida to Newfoundland. Little is known of its life in the ocean, but in spring it approaches the coast in great numbers, and may be had in the St. John's River in Florida in winter, but it is not numerous until March. It next appears in the Savannah and Edisto Rivers, and so successively northward, the height of the run in the Potomac being in April, in the Delaware early in May, and in the Miramichi River in New Brunswick late in May. The main body ascends when the water temperature is 56 degrees to 66 degrees. They come in successive schools, the males preceding the females. They ascend the rivers, often nearly to their heads, and deposit their eggs on suitable spawning grounds, pouring out about 30,000 in most cases. The eggs are very small, semibuoyant, and usually require six to ten days for hatching, depending, as does the whole operation, on favoring temperature. After the spawning the shad show hunger, and will often bite at an angler's fly.

"The herring is beyond question the most important of food fishes in the Atlantic, if not in the world," declared the late G. Brown Goode, formerly Assistant U. S. Fish Commissioner. It affords occupation for immense fleets of boats, and thousands of men, nowhere more numerously than in the North Sea and along the Norwegian coasts. Professor Huxley once gave 3,000,000,000 as the number of herring taken annually from the North Atlantic; but Dr. Goode showed that this was far too low an estimate, and added that it probably was "no greater than the number contained in a single shoal if it covers half a dozen square miles, and shoals of much greater size are on record. And ... at one and the same time scores of shoals must be scattered through the North Sea and the North Atlantic, any one of which would go a long way toward supplying the whole of man's consumption of herring." Herrings are surface swimmers, and their food consists of the small organisms, chiefly crustaceous, which have been described as "plankton" in the early pages of this book. They themselves afford food to every predatory fish, squid, whale, and bird that frequents their region (mainly north of the fortieth parallel of latitude), and which has the wit and ability to seize them. They move here and there in shoals for food, and in spring migrate to the shallows and rivers of the northern coasts to spawn. Besides the Atlantic herring, a very similar species throngs in the North Pacific, and several others live in the Great Lakes and other waters of this country.

No fishes are better known in America than the salmon, trout, and whitefish, which are near relatives. Of the salmon there are many kinds in all the northern parts of the world and in the open ocean. Some ascend rivers to spawn, and some do not. Our Atlantic salmon, once so abundant in every river from Connecticut northward, is the same as the salmon of Europe, and the king of game fish. Now it is at all numerous only in the Maritime Provinces of Canada, climbing the waterfalls of those mountain streams to their very springs to deposit its eggs, whence few individuals survive to return to the ocean. The heaviest salmon on record is one of eighty-three pounds captured in England in 1821; an American example of forty pounds is considered very large.

The salmon of the North Pacific are of a different genus (Onchorhynchus) and consist of several species, some Asiatic. On the American side we have five species, and most of them have been seen in all the rivers from central California to Alaska, Siberia and Japan; but the blueback predominates in Fraser River and in the Yukon; the silver salmon in Puget Sound; the quinnat or Chinook salmon in the Columbia and Sacramento; while the comparatively worthless dog salmon is seen everywhere. The quinnat and blueback enter and "run" the rivers in the spring, and are caught when in prime condition, whereas the other three run in the fall, and are more usually caught after deterioration; hence "spring" salmon are best in fact and in trade.

The habits of the salmon in the ocean are not easily studied, but Jordan, Evermann, and other diligent students have come to certain conclusions from a great number of facts. They believe that the king and the silver salmon probably remain not far from the rivers where they were born. The blueback and dog salmon probably seek deeper water. It is the prevailing impression that the salmons have some special instinct which leads them to return to spawn on the same grounds where they were hatched, but Dr. Jordan says:

"We fail to find any evidence of this. 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 river, or perhaps of any other river, at a considerable distance from shore. In the case of the quinnat and the blueback, 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."

As to the fate of the spawning fish, after the eggs and milt have been voided, and their duty is done, the salmon begin to float downstream tail foremost. The great majority of them die—certainly all at the headwaters of the big streams; and it is the opinion of the best judges that none ever get back from anywhere alive into the ocean after spawning, but that the race is sustained wholly by the escape of the young each year. It is supposed that non return from the sea, or attempt to ascend the rivers until at least three years old.

Trout are in most cases simply small species of salmon, and a great number of kinds inhabit the ocean, lakes, and rivers of all northern countries, for none of this great family occur in the tropics or in the southern hemisphere. Our western trout—the widely distributed and variable cutthroat, the steel-head of the northwestern coast, the beautiful rainbow trout of the Coast Ranges, and others are examples. The common brown "brook" trout of Great Britain belongs here; but our brook trout, the "speckled beauty" of anglers and poets, is of a slightly different kind (genus Salvelinus), for it is classed with the European charrs. The Dolly Varden trout of the Rocky Mountains and the Sunapee trout are also charrs. The graylings, namaycushes, and smelts are members of this family, whose final representative among us is the numerous and very valuable section of whitefish and lake herrings of the Great Lakes and Canada generally.

No family of fish is of more importance as food for man, not to speak of the sport many of its members afford, than this; yet, doubtless, it would have been nearly destroyed by this time had it not been for the intelligent and patient work of fish culturists and the farsightedness of governments, both Federal and State, and Canadian, in supporting and extending economic replenishing of depleted waters. The organization and breeding habits of the salmon tribe lend themselves to this work.

Passing by some families of deep-sea fishes, of small size and most bizarre outlines, we come to the suborder that contains the carps, catfishes and "minnows" of our lakes and streams. Here, the first to present itself, in the large family CharacinidÆ, is that fierce little brute of South American rivers, the "piranha" or "caribe," of which Col. Theodore Roosevelt had so much to say in describing his explorations in Brazil in 1913 and 1914. One of his companions was Leo E. Miller, who has since published another account and increases the bad reputation of the caribe by what he has to tell of its ferocity:

"In the Orinoco they attain a weight exceeding three pounds, and are formidable indeed. The natives will not go in bathing except in very shallow water, and I know of two instances where men were attacked and severely bitten before they could escape. The fish somewhat resembles a bass in shape, although the mouth is smaller; the jaws are armed with triangular, razor-edged teeth; and as they travel in immense shoals they are capable of easily devouring a man or large animal if caught in deep water.... Usually they are slow to attack unless their appetite has been whetted by a taste of blood from a wound; then, however, their work is done with lightninglike quickness.... To catch them we used a large hook secured to a long wire leader and baited with any kind of raw meat, and they always put up a good fight."

A related fish in the Rio La Plata is almost equally dreaded because of its much greater size and formidable teeth, but it works singly; and Africa has many similar characinids, whose flesh is good food, though full of bones. In this order, too, is now classified the family of the "electric eels" (GymnotidÆ) which are not, however, eels, but merely long, cylindrical fishes, naked and almost finless. The well-known one of the Amazon region grows to a length of eight feet and the thickness of a man's thigh, and is justly feared. It is found only in marshes and in comparatively shallow parts of rivers, to the annoyance of travelers who have to ford at such points, beasts of burden being frequently knocked down by the electric shocks. About four-fifths of the length of the fish is occupied by the tail, which contains the electric organ. This consists of two huge masses filled with a jellylike substance, below the spine, and separated by a narrow median septum. This apparatus is under the control of the fish, which by it may stun or kill an enemy or an intended prey, even at a considerable distance.

The family of the cyprinids—the carp, goldfish, chubs, shiners, loaches, and other "minnows" of this and other countries—contains about 1,300 species, scattered over the whole world except South America, Madagascar, and Australasia. All are fresh-water fishes, feeding on vegetation and small animals; and they vary in size from two or three inches to a six-foot carp—the original home of which, now the cosmopolitan giant of the family, was Asia.

Next to these are placed another extensive fresh-water family, that of the catfishes (SiluridÆ). More than 1,000 species, mostly tropical, have been described; these are grouped in eight subfamilies, among which there is a wide diversity in shape and habits—in fact, few of those of foreign lands look at all like the catfishes with which we are familiar in America. Most of them are sluggish, but some actively inhabit swift streams. They can exist not only in foul water, but will live a long time out of this element, and some even make long migrations overland from river to river. One or more fin rays are sharp and poisonous in many species, as boys know who handle the little bullhead incautiously, and an African species is able to administer a strong electric shock. Its apparatus is not a battery of modified muscular tissue, as in other electric fishes, but consists of a thick coat of greasy material surrounding the whole body just beneath the skin. Another general characteristic is the protection and assiduous care given to their eggs and young, most species making some sort of a nest in which the eggs are deposited and the fry kept safe from attack.

The third suborder of teleosts contains eellike fishes of the tropics; and the fourth contains the true eels and their relatives. Our common eel is also "common" in most of the temperate countries of the world, but there are perhaps 150 other species of the family AnguillidÆ, a large proportion of which live altogether in the sea, many of them at great depths, and showing strange shapes. The generation of the eel was, until recent years, one of the great mysteries of zoÖlogy, as no propagation, or any symptoms of it, ever appear in fresh water. Finally it was discovered that a queer, almost transparent, compressed creature, a fraction of an inch long that abounded in the surface waters of the ocean, and which had been a puzzle to naturalists, who called it Leptocephalus, was the larva of some sort of eel. This and other discoveries made it plain that when the eels (of the age of four or five years) leave the rivers and bays of all countries and coasts in the autumn, and go out to sea, they do so to spawn, leaving their eggs on the floor of the ocean, mostly south of Bermuda, according to J. Schmidt. From them hatch the minute larvÆ that, as they grow, rise to the surface, and when about a year old appear as the silvery young, called "elvers," that drift on the northward-running currents to the coasts of Europe and North America, and ascend the streams by millions in spring. It is not probable that any of the adult eels that go down to the sea to spawn ever come back; and if any remain in landlocked waters whence they cannot migrate to the salt water, they do not breed; but it must be remembered that eels are able to travel a considerable distance overland, at night, from one piece of water to another, and so many may finally reach the sea.

The next suborder illustrates the remarkable difference in size and external appearance that often marks fishes grouped together by similarity of structure. It includes the muskellunge and all the other pikes and pickerels, and the tiny shiners and "bait minnows" of our rivers and brooks, and those of the Old World, one of which is the smallest fish known; it includes several families of deep-sea fishes, often of quaint form and with curious appendages; here, too, is the valuable blackfish of Alaska, the amphibious, phosphorescent little fish of Indian bays and estuaries which when salted and dried forms the Oriental delicacy called "Bombay duck"; and here are the blind fishes of the Mammoth and other American caves. The Heteromi and Cateosteomi are almost equally miscellaneous assemblages, the most notable members of the latter being the funny little pipefishes and sea horses that lurk in the eelgrass near shore, and the males of which carry the eggs and young about in a pouch on the belly. In the next suborder, Perceosces, we find more strange denizens of the mid-oceanic depths, especially the family ChiasmodontidÆ, besides some surface ones of ancient lineage, such as the gar and snakeheads of tropical waters, the flying fish and the mullets. The Anacanthini is a small group containing the remarkable pelagic and abyssal macrurids, the fierce barracudas, and the most valuable single family of food fishes in the whole list—the cods.

The cod family (GadidÆ) has many species in northern seas and a few south of the equator. It includes, besides the cods, the haddock, hake, whiting, coalfish, capelin, ling, and several other market fish of importance. The cod is a deep-water fish which goes about in great schools whose movements are not well understood, but in winter they approach the northern shores of the continent, seeking shallows on which to spawn, and it is then on the "banks," off New England and Newfoundland, that the most profitable fisheries are followed. The cod is extraordinarily prolific, and in addition to this it is propagated artificially more extensively than any other fish.

Thus we come to the last suborder, Acanthopterygii, or "spiny-finned" fishes, in which are classified the greater number of really modern and more or less familiar swimmers in the "briny deep." Among American members are the sunfishes and black bass, the perches and darters; the great family (SerranidÆ) of sea bass, snappers and West Indian groupers; the tilefish, which appears and disappears in a puzzling fashion; the grunting drums and their relatives of the ScienidÆ; the porgies, sheepshead, and other SparidÆ; the brilliantly colored angel fish of the coral reefs of Bermuda and southward; the surf fishes, so important in California; the wrasses, parrot fish, and globefishes, or boxfishes, that inflate their horny hides when alarmed, until they bob about on the surface like corks.

FISHES WITH PRIMITIVE LUNGS

There remains the fourth subclass—Dipnoi or Dipneusti, the lungfishes. The reason why these creatures, whose organization is on an antique and lowly plane, judged by fish standards, have been elevated to subclass rank is that here the air bladder is modified into a single or double elongated sac with many cellular spaces, and is connected by a short tube with the mouth, and thus serves as a lung. The peculiar structure of the heart, narial openings, and the power of existing for a considerable period out of water, are extremely amphibianlike, and they have by various naturalists been regarded as scaly sirens—a sort of connecting link between the fishes and the amphibians. They are found fossil in Paleozoic rocks, especially in the Old Red Sandstone of Great Britain, and also in the Upper Jurassic strata in Colorado.

The surviving species (family LepidosirenidÆ) are widely scattered, as is characteristic of all these very ancient families. A celebrated example is the barramundi of Queensland—an elongated, flat-sided fish, covered, except on the head, with large roundish scales, and having paired fins that look more like flippers than fins. It becomes four or five feet long. It lives in still pools in which the water in the dry season becomes extremely stagnant and overladen with decomposing vegetable matter; and it is only by rising to the surface occasionally, and taking air into its lung, that it is enabled to obtain sufficient oxygen for purposes of respiration. The barramundi does not leave the water, nor can it live long in the air. It is easily captured, and is eaten by the blackfellows.

Equatorial Africa possesses three species of the genus Protopterus, which dwell in marshes, and feed voraciously on young fishes, frogs, and small animals. The form is somewhat eellike, and the paired fins are soft, slender appendages of little use, locomotion being effected by the powerful tail. Like the barramundi this fish rises at intervals to take a breath of air; its "lungs" are double, while that of the barramundi is single. In the dry time of summer the protopterus burrows deeply into the mud of the dried-up marshes, where it curls up with its head highest and subsists wholly by breathing air until the autumnal rains bring water enough to enable it to wake up and resume its aquatic life. A similar eellike species abounds in the swamps, sluggish rivers and marshes of northern South America, named Lepidosiren, and all its habits closely resemble those of the African lungfishes.