370 



A MANUAL OF DENTAL ANATOMY. 



and forward motion, made use of in gnawing, is very con- 

 siderable. The Leporidce are exceptional in having more 

 lateral play than most Rodents. And the power of the 

 teeth is marvellous ; rats will sometimes gnaw holes in 

 water-pipes, or in gas-pipes, in which they have heard water 

 bubbling. 



The general character of a Rodent's dentition may be 

 illustrated by a description of that of the Capybara. 



FIG. 160 



The incisor teeth are squarish. They are wider than 

 they are deep, and are slightly grooved on their anterior 

 surface. 



There are four grinding teeth on each side, of which the 

 first three are small, and with few cross plates of dentine 

 and enamel, but the fourth is a very complex tooth, with 

 twelve or more such plates, which are fused into a solid 

 mass by cementum. 



The tooth being one of persistent growth, there is no 

 common pulp cavity, but each plate has its own. 



It has already been mentioned (page 160) that the den- 



( l ) Cranium of Capybara. 



