JR. S. Lull — Evolution of the Elephant. 193 



The grinding teeth were of large size, two in each half of 

 either jaw, as in the Tetrabelodon, but the crests are simpler 

 with but few accessory cusps. The crown of the tooth is 

 covered with thick enamel, which in turn is overlain by a thin 

 layer of cement before it cuts the gum. This is soon removed 

 by wear. These teeth are admirably adapted for crushing- 

 succulent herbage such as leaves and tender twigs and shoots, 

 but not for grinding the siliceous grasses which form a neces- 

 sary part of the food of the true elephants. " Broken pieces 

 of branches varying from slender twigs to boughs half an inch 

 long" have been found within the ribs of a mastodon together 

 with " more finely divided vegetable matter, like comminuted 

 twigs to the amount of four to six bushels.'* 1 " Twigs of the 

 existing conifer Thuia occidentalis were identified in the 

 stomach of the New Jersey mastodon, while that of New- 

 burgh, N. Y., contained the boughs of some conifer, spruce 

 or fir, also other not coniferous, decomposed wood. A news- 

 paper account of the finding of the great Otisville mastodon, 

 now preserved at Yale, says that the region of the stomach 

 contained " fresh-looking, very large leaves, of odd form, and 

 blades of strange grass of extreme length and one inch to 

 three inches in width." 



The Yale collection contains numerous specimens of the 

 American mastodon, including the nearly complete skeleton 

 from Otisville, N. Y., soon to be mounted, another fairly com- 

 plete skeleton of a younger individual from Urbana, Ohio, 

 and many jaws and teeth. There are also specimens of the 

 apparently ancestral M. horsoni from England. 



True Elephants. 



In order to trace the evolution of the true elephants we 

 must go back once more to the/ Upper Miocene of southern 

 India to the form known as Mammul latidens. This creature 

 gave rise to a species variously known as Mastodon elephan- 

 toides or Stegodon clif'ti, for its transitional character is such 

 that authorities differ as to whether it is a mastodon or an 

 elephant. 



Stegodon. 



In Stegodon the molar teeth have more numerous ridges 

 than in the true mastodons and the name Stegodon is given 

 because of the roof-like character of these ridges, the sum- 

 mits of which are subdivided into five or six small, rounded 

 prominences. There is a thin layer of cement over the 

 enamel in an unworn tooth but no great accumulation in the 

 intervening valleys as in the elephants. These teeth show 

 how slight the transition is, however, merely a filling of 



