THE EVOLUTION OF MAN 



189 



The Man-Like Apes. The family Simiidae includes four existing 

 genera: Hylobates, the gibbons; Simia or Pongo, the orang; Pan, 

 the chimpanzees (Fig. Ill); and Gorilla, the gorilla (Fig. 112). 

 All of these animals are tailless. Though they can walk in a semi- 



FiG. HI. — Chimpanzee, Pun pyqmaem. (From Lull, photograph from the 



New York Zoological Society.) 



erect position, touching the knuckles to the ground to aid their 

 progress, they are predominantly arboreal with the exception of 

 the gorilla. The opposable thumbs and great toes provide them 

 with four grasping appendages which are very effective for moving 



