BRANCH CHORD AT A : CLASS MAMMALIA 401 



less developed in the lemurs than in any of the other 

 monkeys. The monkeys and apes may be divided into 

 two groups, the lower, platyrrhine monkeys, found in the 

 New World, and the higher, catarrhine forms, limited to 

 the Old World. The platyrrhine monkeys have wide noses 

 in which the nostrils are separated by a broad septum and 

 with the openings directed laterally. These monkeys are 

 mostly smaller and weaker than the Old World forms and 

 are always long-tailed, the tail being frequently prehen- 

 sile. They include the howling, squirrel, spider, and 

 capuchin monkeys common in the forests of tropical South 

 America. The catarrhine monkeys have the nose-septum 

 narrow and the openings of the nostrils directed forwards, 

 and the tail is wanting in numerous members of the group. 

 They include the baboons, gorillas, orang-outangs, and 

 chimpanzees. These apes have a dentition approaching 

 that of man, and in all ways are the animals which most 

 nearly resemble man in physical character. 



