Chap. IV.] 



TEETH OF FISHES. 



143 



a 



function ; indeed, in very many fishes the food is 

 swallowed whole. 



Owing to the fact that these Vertebrates are not 

 able to put their fins to the duty of seizing their food 

 in the way in which many higher forms use their 

 anterior pair of limbs, the teeth may often be observed 

 to have a special prehensile function. This power is 

 sometimes developed to an extraordinary degree ; all 

 the numerous teeth in the mouth of the pike are 

 directed backwards, and so prevent or oppose the 

 escape of any prey which has been taken into the 

 mouth ; an extension of this arrangement has been de- 

 scribed in the angler (Lophius), where some of the 

 larger teeth in the front of the mouth are so attached 

 to the edge of the jaw that they spring up again as 

 soon as the food 

 which has pressed 

 them downwards 

 into the mouth 

 has passed them 

 and entered the 

 oral cavi ty 

 (Tomes). By 

 this means the 

 prey is caught as 

 in a trap. 



Where the 

 teeth are used for 

 the purposes of 

 breaking up the food or the shell in which it is con- 

 tained, they become of considerable size, as in the 

 Wrasses ; in the parrot- Wrasses (Scarus) the teeth un- 

 dergo fusion with their neighbours ; in the sheep's-head 

 (Sargus) the teeth in the front of the mouth are cutting 

 organs, and those at the sides larger, and have their 

 surface rounded, so that, as they move on one another, 

 they act as grinders. Where a number of teeth are 



'ig. 63. Lower pharyngeal Bone of Scants, 

 showing Teeth of different Ages. Two-thirds 

 natural size. (After C. S. Tomes.) 



