THE ATTACHMENT OF TEETH. 203 



of moveable teeth, able to yield to pressure and subsequently 

 to resume the upright position, was formerly supposed to be 

 confined to the Lophius (Angler) and its immediate allies. 

 I have however found hinges in the common Pike (Esox), 

 and in the Gadidce (Cod tribe) ; so that, as they occur in these 

 fish so widely removed from one another in other respects, it is 

 probable that further investigation will bring to light many 

 other examples of this very peculiar method of attachment, 

 eminently suited to, and hitherto only discovered in, fish of 

 predatory habits. 



In the Angler, which obtains its food by lying in ambush 

 on the bottom, to which it is closely assimilated in colour, 

 many of the largest teeth are so hinged that they readily 

 allow an object to pass into the mouth, but rebounding 

 again, oppose its egress. These teeth are held in position 

 by dense Iioro^s ligaments radiating from the posterior side 

 of their bases on to the subjacent bone, while the fronts of the 

 bases of the teeth are free, and when the teeth are pressed 

 towards the throat, rise from the bone. The elasticity of 

 the ligament is such that when it has been compressed by 

 the tooth being over towards it, it returns it instantly into 

 position with a snap. Many of the teeth of the Angler are, 

 like most fishes' teeth, anchylosed firmly. 



The Hake (Merlucius, one of the Gadidce) possesses two 

 rows of teeth, the inner and shorter of which are anchylosed, 

 whilst the outer and longer are hinged. 



In some respects these hinged teeth are more highly 

 specialised than those of the Angler, which they resemble 

 in being attached by an elastic hinge fixed to their inner 

 sides, the elasticity of which is brought into play by its being 

 compressed, or at all events bent over, upon itself. 



The pulp is highly vascular, and its vessels are so arranged 

 that, by entering the pulp through a hole in the ligament, 

 which is about at the axis of motion, they escape being stretched 

 or torn during the movements of the tooth. But the base 



