THE RECESSION OF THE SNOUT REGION S7 



kill it with its teeth. I have seen Nycticebus tear grasn- 

 hoj)pers to pieces with its hands, but Ijirds it always 

 killed by biting. The monkeys were adepts at catchinpr 

 birds, and although chained they had no diffioulty in 

 seizing the confiding Java sparrows that were attracted 

 by their food. The bird was caught in one hand, and 

 was then killed by being pulled and twisted between the 

 two hands. Generall}^ the monkey wrung the bird's neck 

 so thoroughly that it succeeded in pulling it altogether 

 apart; it killed with its hands, and then conveyed the 

 kill to its mouth with its hands. 



In the Primates, owing to the preponderant use of the 

 fore-limb, there is no need for a mouth which reaches out 

 for food, or for a mouth which seizes food or kills it when 

 seized, all these functions being discharged by the moljile 

 and grasping fore-limb. 



Now teeth are developed for different purposes. They 

 are developed for cutting herbage, for seizing animal 

 food, and for killing prey as well as for biting it up j^re- 

 paratory to swallowing. Some teeth subserve the func- 

 tion of obtaining a variety of food in a variety of ways, 

 and some subserve the function of preparing this food for 

 the processes of digestion. With the adaptation of the 

 hand for obtaining food, the need for the specialization 

 of teeth for this purpose will no longer be felt so strongly, 

 and it is natural to suj^pose that the tooth series will 

 become abbreviated, only those teeth which are necessary 

 for dealing with food brought to them by the hand 

 remaining fully functional. We may assume, as a ground- 

 plan of the mammalian tooth series, an upper and a lower 

 set, composed of three incisors, one canine, four pre- 

 molars, and three molars upon each side of the jaw. 

 Such a tooth series comprises forty-four teeth, and it 

 is seen, for example, in the elongated jaws of the 

 omnivorous pig. 



If we trace this tooth series through the Primates rnd 

 their probable next of kin, we find the full forty-four in 



