We come now to the fishes proper—those with skeletons of bone, although in some of the lower forms the ossification is incomplete. The mouth contains supplementary tooth-bearing bones that form secondary jaws corresponding to the functional jaws of the higher craniates; hence the group name "Teleostomi," or perfect-mouthed fishes. The body, as a rule, is coated with scales, and a gill cover (operculum) is always present.

The Teleostomi include four orders, the Crossopterygii, the Chondrostei, the Holostei, and the Teleostei.

The crossopterygians are mostly strange extinct fishes found as fossils from the Devonian down; but some have survived, and live in the sluggish African rivers an eellike existence, of which the bichir of the Nile is a familiar example. The Chondrostei also are largely fishes of the Paleozoic time, but two families survive to the present—the spoonbills and the sturgeons. Of the former one species is Chinese, and the other is the shovel-nosed spoonbill or paddlefish of the lower Mississippi River. It is a big, sluggish creature, that stirs up the mud with its long flat beak, and consumes it, getting sustenance from the minute organisms it contains. They make caviar from its eggs. As for the sturgeons, we have five species in the United States, and one abounds in the Black Sea and the rivers that drain into it, from whose eggs the Russian caviar is made. One or two species are exclusively fresh-water, but most sturgeons are migratory fishes, living in the sea, but ascending rivers for spawning. Their food consists of worms, mollusks, the smaller fishes and aquatic plants; and in feeding the mouth is protruded downward in the form of a cylindrical, spout-like structure and thrust into the mud. Our common eastern-coast sturgeon is also a native of the Mediterranean and French coasts, and was formerly in England a "royal" fish, reserved to the king's use.

Of the third order, Holostei or "ganoids," whose history may be traced in fossils almost to the earliest of fossiliferous rocks, we possess in our rivers the only two survivors: one is the many-named bowfin of the Mississippi Valley, and the other the widely distributed billfish or gar pike. Both these relics of a very ancient order are of great interest to naturalists; and the names "mudfish," "John H. Grindle," and many others, show how well known the bowfin is to the farmer boys. The bowfin attains a length of about two feet and a weight of twelve pounds, and, unlike its cousins the garfishes, is covered with hard, rounded scales; the forepart of the body is cylindrical, the head stout and blunt, and the mouth filled with powerful teeth. It is exceedingly hardy, enduring absence from the water for a long time, as well as grievous injury; hence the young are the favorite bait of anglers in the Mississippi Valley, and make interesting captives in an aquarium, where, however, nothing else but snails can remain alive. These fish are strong, active, voracious and gamy. They feed on all sorts of small aquatic creatures.

The garfish (or more properly gar pike, Lepidosteus, because certain sea fishes of another sort are also called gars) is an elongated active fish of our rivers, covered with hard, flat, ivorylike scales set in oblique rows, and its snout is prolonged into a bill filled with sharp teeth. They have many peculiarities of structure indicating their ancient ganoid lineage; and besides our common species two others are known, one of which, the alligator gar, belongs to the Gulf Coast and Central American rivers. These gars are nocturnal and predatory in their habits, and in early summer resort in large numbers to shallows to lay their eggs, which are covered with a sticky envelope that adheres to any object on which they fall. The long bill develops after infancy.