THIRD STAGE OF THE HISTORY. 



White-throated Sapajou {Cebus hypoleucus), a platyrrhine monkey of tropical America. .The 

 platvrrhine apes were the ancestors of the catarrhine forms, and therefore represent another 

 step as we ascend the familv tree of Homo sapiens. It is, of course, not to be understood 

 that thi'^ or any of the other mammals shown in this series are considered ancestors ot man; 

 but it is to be thought that this vSapajou and the present primates, mcludmg nian, are both 

 descended from a platyrrhine form of the old world, which has probably undergone very 

 little change in its descent to the sapaiou, but from which man's ancestors diverged through 

 forms like the langur and gibbon. Photographed by Elwm R. Sanborn of the New York 

 Zoological Society. (Fig. 2.) 



