Page:Natural History, Fishes.djvu/25

Rh Herring and Pilchard for example, have similar thread-like branches sent off from each of the vertebræ; so that the bodies of these fishes seem filled with long and slender bones.

The skull varies much in form in different tribes, but in general consists of pieces answering to those which compose the head of the other. Teeth are generally very numerous; and are found in almost every one of the bones that enter into the composition of the mouth, though not in all the species. They are generally simple spines, curved backwards, but innumerable modifications of this form occur. Thus the jaws of the deadly Shark are flat and lancet-like, the cutting edges being notched like a saw; the front teeth of the Flounder are compressed plates; some, as the Wrasse, have flat grinding teeth; others, as the Sheep's-head, have the grinding surface convex; and others, as the genus Chrysophrys, have convex teeth so numerous and so closely packed over a broad surface, as to resemble the paving-stones of a street. The beautiful Chætodons of warm climates, on the other hand, have teeth which resemble bristles, and these are set close together like the hairs of a brush; while the Perch of our own rivers have them still more slender, minute and numerous, so as to resemble the pile of velvet. Another of our well-known fishes, the bold and fierce Pike, is armed with teeth scarcely less formidable in size, form, and sharpness, than the canines of a carnivorous quadruped. In number also there is great variety. The Pike, the Perch, the Catfish, and many others, have their mouth crowded with innumerable teeth, while the Carp and the