192 



i?. S. Lull — Evolution of the FAephant. 



Mammut. 



This genus readies its culmination in the American masto- 

 don, a creature of great bulk, though about the height of the 

 Indian elephant. It was, however, much more robust, a 

 feature especially noticeable in the immense breadth of the 

 pelvis and the massiveness of the limb bones. The feet were 

 more spreading than in the true elephants, which, together 

 with the character of the teeth, and the conditions under 

 which the remains are found, points to different habits of life 

 from those of the mammoth, the mastodons being more dis- 

 tinctively forest-dwelling types. The skull differs from that 

 of the true elephants in its lower, more primitive contour, for 

 while there is a large development of air cells in the cranial 

 walls the brain cavity is relatively larger. The tusks are well- 



Fig. 19. Skull of the American Mastodon. 



developed, powerful weapons, not so sharply curved as in the 

 elephants, though in this respect individuals vary. The tusks 

 are very heavy at the base and taper rapidly, curving inward 

 at the tips. In the lower jaw the tusks are vestigial, being 

 apparently present only in the male. Usually they are soon 

 shed and the sockets may entirely disappear as in the Otis- 



Fig. 20. Tooth of Mastodon ( x i). 



ville mastodon at Yale, whereas the Warren mastodon now in 

 the American Museum, a fully adult animal, retained the left 

 lower tusk, which is about eleven inches in length. The 

 socket of the right tusk is also still distinct. A cast of the 

 symphysis of the lower jaw of a young animal containing 

 one tusk is exhibited at Yale. 



