138 REPTILES 



From horny beaks, with or without a pair of tusks in the 

 upper jaw, the transition is easy to teeth, since both, in a greater 



Fig. ii. — A, skull of Iguanodon, to show predentary bone and edentulous 

 fore part of jaw. B, skull of Dicynodon, showing single pair of upper tusks, 

 and horny beak. C, skull of Carnivorous Mammal-like Reptile (Galesaurus) to 

 show differentiated dentition. A and B from Guide to Fossil Reptiles, etc., in 

 British Museum {Natural History). 



or lesser degree, are connected with the nature of the food, and 

 are therefore to some extent, at any rate, adaptive in this re- 

 spect. Furthermore, the teeth may also be intimately connected 



