MEMOIRS. 



On the Hinged Teeth of the Common Pike. By Chatiles 

 S. Tomes, M.A. (With Plate I.) 



Notwithstanding the activity of biological research in 

 almost every other direction, it has happened that the teeth^ 

 more especially of reptiles and fishes, have received but little 

 attention, and thus many most interesting peculiarities, 

 although met with in creatures exceedingly common, have 

 escaped notice. The angler {Lophius piscatorlus) has long 

 been known to possess hinged teeth, capable of being bent 

 inwards towards the mouth, but by virtue of the elasticity 

 of the hinge at once resuming the upright position when 

 pressure is removed from them ; this arrangement was 

 formerly supposed to be peculiar to the angler, but Professor 

 Owen ('Anatomy of Vertebrates,' 1866) added Anableps 

 and Poecilia to his list of fish with movable teeth. 



In the course of last year I found that the Hake, a 

 voracious predatory fish, and in a less degree other Gadidae, 

 were possessed of hinged teeth ; and shortly afterwards I 

 found a similar condition in certain regions of the mouth of 

 the common pike (' Proc. Royal Soc.,' No. 179, 1877). The 

 structural peculiarities in the attachment of the teeth of the 

 Gadidae having been briefly described in the paper alluded 

 to, now in course of publication in the ' Philos. Trans.,' I 

 will confine myself in the present communication mainly to 

 the teeth of the pike, merely noting some points of difference. 



The hinged teeth with which I am acquainted have certain 

 characters in common ; they are all capable of being bent 

 down by very slight pressure, but in a single direction only ; 

 to force applied in any other direction, they are rigidly 

 immovable. This direction, with certain variations to be 

 described, is inwards and backwards towards the gullet, so 

 as to facilitate the ingress and the swallowing of food; on 

 the removal of the pressure they rebound to their upright 

 position. It appears to me very probable that adequate 



VOL. XVIII. NEW SER. A 



