THE TEETH OF PRIMATES. 407 



one of the lemurine animals which are to be found there has 

 been so modified that its teeth to all intents and purposes 

 are those of a rodent. Yet with all this modification it 

 retains characters (notably its milk dentition) which are 

 quite unlike those of true rodents, but which recall the 

 manner of its origin from higher lemurine forms. 



SimiacUe. The true monkeys are divided into two 

 great divisions, the new world monkeys and the old world 

 monkeys. The former differ in many respects from the 

 latter ; for the most part they have prehensile tails, and 

 their nostrils are set somewhat widely apart, whence 

 they are called Platyrrhine, or wide-nosed monkeys, and 

 they differ also in their dental formula, which is 



.2 1 3 3 0/ , 

 i-_o rP -m- = 36. 



The little marmoset monkeys have only 32 teeth, but they 

 agree with the other new world monkeys in having three 

 premolars on each side, the molars being reduced to two in 

 number. The upper molars of many new world monkeys 

 have the antero-internal and extero-posterior cusps joined 

 by an oblique ridge, a character which is shared in the old 

 world groups by man and the anthropoid apes only. 



All the Quadrumana have a well developed milk den- 

 tition. 



Old world or Catarrhine monkeys all have the same 

 dental formula as man 



.212 3 



As an example the Macaque monkey may be taken. The 

 upper and lower incisors, but especially the former, are 

 directed obliquely forwards, and the^ lateral incisors are very 

 much smaller than the centrals. In the upper jaw a con- 

 siderable interval separates the incisors from the canine, 



