148 



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, PHocene; C, C, Mastodon, Pleistocene; 

 D, D', Trilophodon, Miocene; E, E' , Palacomastodon, Oligocene; F, F', Mac- 

 ritherium, Eocene. {From Lull.) 



