GREGORY: NOTHARCTUS, AN AMERICAN EOCENE PRIMATE 



239 



Homo sapiens. Human stage: advanced adap- 

 tations for erect posture. Hallux dominant, fac- 

 ing downward and permanently adducted; other 

 digits much shortened. Tarsus very large, with 

 down-lurned heel and arched instep. 



Gorilla sp. Amer. Mus. No. 35400. Young 

 gorilla representing advanced anthropoid stage, 

 adapted both for climbing and for semi-erect pro- 

 gi'ession on the ground. Hallux powerful, digits 

 relatively short. Tarsus large, with down-turned 

 heel. 



Macacus nemestrinus. (Amer. Mus. No. 14012). 

 Catarrhine stage: pes adapted both for running 

 and grasping. Digits long. 



Cehus hypoleucus. (Amer. Mus. No. 14016). 

 Platyrrhine stage: with mobile hallux. 



Nothardus osborni. (Amer. Mus. No. 11474). 

 Primitive primate stage: with long digits, weak 

 flexors and very large, sharply divergent hallux. 



Didelphis mrginiana. Primitive arboreal un- 

 guiculate stage : with short digits, powerful flexor 

 muscles and strong divergent hallux. 



Fig. 84. Comparative series: pes of Didelphis, Nothardus, and higher primates. 



