318 TOWARDS THE HUMAN FORM 



Orang-Outangs of the Sunda Islands, the Chimpanzees, and 

 the Gorillas of Central Africa have lost their tails, and the 

 absence of this appendage accentuates their resemblance to 

 Man. They are called Anthropomorphous Apes, i.e. apes 

 shaped like Man. 



At the beginning of the Eocene Period there lived in America 

 numerous species of Lemurs (Hyopsodus), which lacked only 

 one pair of incisors to conform to the complete dental formula 

 of the early placental Mammals, with its four molars and three 

 premolars. We may perhaps even consider Pelycodus of 

 the Wasatch, which did conform to the complete dental 

 formula, to be Lemurs. But we may say that true Primates 

 in this period are characterized by a reduction of their incisors 

 to two pairs, which persisted throughout the whole series. 

 Animals of the Upper Eocene with an analogous dental 

 formula — Adapts — have been found in the basin of Paris ; 

 but Cuvier, who was the first to describe them, had only seen 

 their skulls, and took them for Pachydermata. Further, the 

 angle of the lower jaw is slightly curved inward, as in 

 the Marsupials. Adapts is therefore very near to the 

 primitive placental Mammals, and we are thus led to admit 

 that the Primates evolved on parallel lines to the other 

 placental Mammals, without mingling with them The Lemurs 

 form a highly diversified group, as witness the long muzzles 

 and straight, pointed ears, giving them a special physiognomy 

 which has earned them the description of Fox-faced Monkeys, 

 the multiple mammae and varied dentition sometimes including 

 only one pair of lower incisors (Propithecus, Tarsius), and some- 

 times only a single one in the upper jaw (Aye-Aye), which, thus 

 deprived of canines, resembles that of a Rodent — all of which 

 characters go with a retention of the four prehensile hands. 

 Some lemurian forms have given rise to the American Monkeys, 

 which have retained their four primitive premolars. The 

 Lemurs were distributed throughout the world, and it is very 

 likely that somewhere in this varied group the ancestors of both 

 New and Old World Monkeys evade us. For, even though both 

 these ancestors were Lemurs, they need not necessarily have 

 been identical. The New World Monkeys have a maximum of 

 thirty-six teeth, those of the Old World only thirty-two. But 

 these two types differ among themselves, because the New- 

 World Monkeys have a milk dentition which always includes 



