FISHES. 
259 
Teeth, which are so characteristic of Vektebrata, are 
nowhere found in such variety of form and function as 
among Fishes. They are not confined to the jaws, but 
are found by turns in almost every one of the bones that 
compose the mouth, though not in all species. They are 
generally simple spines, curved backwards; but innume- 
rable 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 
Plaice and 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 Clirysophrys, have convex teeth so 
numerous and so closely packed over a broad surface, as 
to resemble the paving-stones of a street. The beautiful 
Chsetodons of warm climates, on the other hand, have 
teeth which resemble bristles, and these aro set close to- 
gether like the hairs of a brush ; while the Perch of our 
own rivers has them still more slender, minute, and nume- 
rous, 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 sharp- 
ness, than the canines of a carnivorous quadruped. In 
number, also, there is a great variety. The Pike, the 
Perch, the Cat-fish, and many others, have the mouth 
crowded with innumerable teeth, while the Carp and the 
the Roach have only a few strong teeth in the throat, and 
a single flat one above; and the Sturgeon, the Pipe-fish, 
and the Sandlaunce, are entirely toothless. 
The eye in this Class presents a beautiful example of 
adaptation to the medium in which they live. From the 
