44 ANATOMY AND PHYSIOLOGY 



TEETH. 



Whilst some species of fish are distinguished 

 for the number and pecuHarity of their teeth, oth- 

 ers are as remarkable for having none at all. In 

 those in which they are developed, they are cha- 

 racterized by being usually small, in proportion to 

 the bulk of the animal, sharp pointed, and calcu- 

 lated for retaining a hold of prey, — the articula- 

 tion of the jaws admitting of no side-way motion, as 

 in mastication. When teeth are found on the 

 margin of the jaws, they generally may be detect- 

 ed also in the fauces and throat, quite down into 

 the gullet. Sharks are without rivals, as it re- 

 spects the number and ofhce of their teeth. Many 

 of them have six and seven rows, spear-pointed, 

 with cutting edges, like lancets, hooking inward 

 towards the throat. Each tooth has its muscles 

 for erecting or depressing it. There Is nothing 

 analogous to this, in the whole range of natural 

 history. Their mouths are only humbly imitated 

 in common mouse-traps ; — the admission is easy, 

 but an exit is literally impossible. 



Fishes that feed on shell-fish, as clams, oysters, 

 crabs, &:c., have no teeth in the gums, as they 

 would be soon broken in seizin;^^ such hard sub- 

 stances. But beyond, the palate and throat 

 are thickly studded with large bony knobs, re- 

 sembling the double teeth of man, beautifully 



