THE TEETH OF REPTILES. 247 



process, but an English snake can swallow a moderate-sized 

 frog with considerable rapidity. 



There is an African snake (Rachiodon) which has none but 

 rudimentary teeth; its food consists of eggs, which thus 

 escape breakage until they reach the oesophagus, into which 

 spinous processes from the under surface of the vertebrae 

 project, and there serve to break the egg; snakes with 

 their dentitions similarly modified exist also in India (e.g., 

 Elachistodon). 



It has already been mentioned that the non-venomous 



FIG. 104 !. 



snakes have two complete rows of teeth in the upper jaw, 

 the outer row being situated on the maxillary bones, the 

 inner upon the palatine and pterygoid bones. The teeth of 

 such snakes as the Pythons are all simple recurved cones, 

 and^, are none of them either grooved or canaliculated. 2 



0) Head and jaws of Hydrophis. The maxillary bone (6), instead of 



carrying a complete series of teeth, is armed with a few teeth only near to 



the front. The foremost tooth is canaliculated, and forms the poison fang. 



( 2 ) It has been proposed to divide the Ophidia into groups, distinguished 



*by the presence or absence of grooved teeth, thus : 



i. Agfypkodontia. No grooved or canaliculated maxillary teeth, 

 ii. Opisthoglyphia. Some of the posterior maxillary teeth grooved, 

 iii. Protcroylypliia. Anterior maxillary teeth grooved. 



Posterior maxillary teeth solid. 



iv. Solenoglyphia. Maxillary teeth few, canaliculated poisonous 

 snakes. 



