3-3 0-0 4-4 



3-3 



3^3 C - 0=0 P ' m -^4 



m. — 



3-3 



THE TEETH OF MAMMALS 167 



The Eliinoceros has the formula, — 



40, 



when the full quota is present. The incisors of 

 the Eliinoceros (Fig. 72) bear an inverse relation- 

 ship to the development of horns, — i.e., when the 

 horns are present the incisors are reduced or ab- 

 sent, and when the horns are absent these teeth 



Fig. 72. — Teeth of Rhinoceros (species unknown). 



are augmented. The two-horned species have no 

 incisors in the adult individual. The incisors 

 vary from four to eight, — some having the cen- 

 trals missing and others the laterals. The ca- 

 nines are absent in all species. The grinding 

 teeth increase in size from before backward, and 

 differ from those of the horse by being implanted 

 by distinct roots. They present a characteristic 



