662 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



Fig. 20.— Stegodon tooth (X i). 



the creature was also of great size. It is first found in the Lower 

 Pleistocene (Forest Beds) of Norfolk, England. In the Thames Val- 

 ley deposits i< was contemporaneous with early man, and for a while 

 Avith Elephas primigenius^ the hairy mammoth. E. antiqwis was 



essentially an animal of warm climate, 

 giving way to the mammoth when the 

 arctic conditions of the glacial period 

 arose. 



In North America, during the cooling 

 to cold climatic conditions 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 mi- 

 grant from the Eurasian continent. This species appeared in the 

 Lower Pleistocene (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. 



Elephas iinperator was of 

 great size, 13^ feet in height at 

 the shoulder, and the huge, 

 spiral tusks measured 13 feet 

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

 of Mexico is said to be 16 feet in length ! 



Elephas colwmbi^ the Columbian mammoth, is thought by some 

 authorities to be but a variety of E. primigenius^ the teeth being tran- 

 sitional in the character of the la- 

 mellae between the latter and E. im- 

 perator. In fact, they greatly re- 

 semble those of the modern Indian 

 elephant. E. colmnhi was early and 

 middle Pleistocene in distribution, 

 more southern in range than E. 

 primige?iius, though the two in- 

 habited a broad frontier belt along 

 the northern United States. E. co- 

 lumhi reaches the maximum of evolution in the shortening and height- 

 ening of the skull. The tusks in a mounted specimen in the American 

 Museum of Natural History are so huge that their tips actually curve 

 backward and cross each other. They have completely lost their 



Fig. 21. — Tooth of E. imperator (X I). 



Fig. 22. — Tooth of E. columU (X 4). 



