TEETH OF MONKEYS AND LEMURS. 807 



g g g g 



Most of tlie LemurincE have p .m , together with 



O O O O 



remarkable modifications of their incisive and canine 

 teeth, of which an extreme example is shown in the pecti- 

 nated tooth of the galcopitheciis. The inferior incisors 

 slope forwards in all, and the canines also, which are 

 contiguous to them, and very similar in shape. 



In the hoofed quadrupeds Avith toes in uneven number 

 {peTLSsodactyla\ whose premolars, for the most part, repeat 

 both the form and the complex structure of the true 

 molars, such premolars are distinguished by the same 

 character of development as those of the artiodacUjla^ or 

 ungulates, with toes in even number ; although here the 

 premolars are distinguished also by modifications of size 

 and shape. The complex ridged and tuberculate crowns 

 of the second, third, and fourth grinders of the rhinoceros, 

 hyrax, and horse, no more prove them to be true molars 

 than the trenchant shape of the lower carnassials of the 

 lion proves them to be false molars. It is by develop- 

 ment alone that the primary division of the series of 

 grinding teeth can be established, and by that character 

 only can the homologies of each individual tooth be de- 

 termined, and its proper symbol applied to it. 



In Fig. 72, the three posterior teeth of the almost uni- 

 form grinding series of the horse's dentition are thus 

 proved to be the only ones entitled to the name of "true 

 molars ;" and, if any one should doubt the certainty of 

 the rule of counting, by which the symbols, /> 4, ^ 3, and 

 p 2, are applied to the three large anterior grinding teeth 

 (i&.), which are commonly the only premolars present in 

 each lateral series of the horse's jaws, yet the occasional 

 retention of the diminutive tooth {p 1), would establish 

 its accuracy, whether such tooth be regarded as the first 



