140 



EVOLUTION, GENETICS, AND EUGENICS 



North America, Europe and Asia; Stegodon from the Pliocene of 

 southern Asia; and Elephas from the Pleistocene of the Americas, 

 Europe, and Asia, as well as the living elephants of Asia and Africa. 



Fig. 34. — Evolution of head and molar teeth of mastodons and elephants. 

 A, A', Elephas, Pleistocene; B, Stegodon, Pliocene; C, C, Mastodon, Pleistocene; 

 D, D', Trilophodon, Miocene; E, E' , Palaeomastodon, Oligocene; F, F', Moe- 

 rithcrium, Eocene. {From Lull.) 



