THE TERTIARY PERIOD 



323 



mals, characterized by the proboscis (trunk), has been traced 

 through many intermediate forms back to primitive Eocene 

 ancestry. Proboscidians culminated in the Pliocene, when they 

 were the largest (up to 13 or 14 feet high), the most numerous, and 

 widespread over much of the earth except Australia. Mastodons, 

 now wholly extinct, are characterized by having knob-like promi- 



Fig. 205 

 A Mammoth Elephant, Elephas primigenius, restored by C. R. Knight. (Per- 

 mission of American Museum of Natural History.) 



nences on the chewing surfaces of their large teeth (Fig. 204a), 

 while the true Elephants (including the extinct Mammoths) have 

 large nearly flat grinding surfaces on their teeth (Fig. 204b) . True 

 Elephants also nearly always show greater curvature of the tusks. 

 The Mammoth had long brown hair (Fig. 205) . 



The accompanying sketches (Fig. 206), together with the 

 following excellent summary by Lull, will give a good idea of the 

 evolution of the Proboscidians. " Increase in size and in the de- 



