1j3g jaws of ptychodus fkom the chalk. [may 1 904, 



Discussion. 



1 



Prof. Seeley remarked on the great interest of the communication, 

 as establishing the possibility of the existence of an intermediate 

 group between the Sharks and the Kays. The specimen brought) 

 forward by the Author showed that, while the dentition in Ptychodus 

 was parallel, the jaws protruded forward in a way never observed 

 in typical Rays ; and while the teeth of Ptychodus were undoubtedly 

 used for crushing, the jaw was prehensile. 



