196 R. S. Lull — Evolution of the Elephant. 



tions of Pleistocene time, there were three species of Elephas 

 of which the most primitive in point of tooth structure was the 

 great imperial elephant, E. imperator, a migrant from the 

 Eurasian continent. This species appeared in the Lower Pleis- 

 tocene (Equus or Sheridan beds) and, while it ranged from 

 Ohio to California, was more southern in distribution, ranging 

 as far as Mexico and possibly into French Guiana. In this 

 species the grinding teeth were of enormous size with very- 

 coarse lamellae and the outer covering of cement was ex- 

 tremely thick. 



Fig. 23. Tooth of E. imperator ( x £). 



Elephas imperator was of great size, 13 J feet in height at the 

 shoulder, and the huge, spiral tusks measured thirteen feet 

 along the curve by 22 inches in circumference. One tusk in 

 the city of Mexico is said to be sixteen feet in length ! The 

 collection at Yale contains one molar tooth of Elephas imper- 

 ator from Mexico, one from Ohio, and the right ramus of the 

 lower jaw containing a single molar from Alameda county, 

 California. An upper molar of this same individual is in the 



Fig. 24. Tooth of E. columbi ( x £). 



Amherst College museum, while a portion of the tusk is in that 

 of W abash College. 



Elephas columbi. the Columbian mammoth, is -thought by 

 some authorities to be but a variety of E. primigenius, the 

 teeth being transitional in the character of the lamellae between 



