132 Bulletin America?i Museum of Natural History. [Vol. XIV, 



specimens come from practically the same locality, the type 

 localities being less than one hundred miles apart; there- 

 fore as there seems to be absolutely nothing upon which to 

 separate these species, there is no alternative but to consider 

 E. ecus {E. intennedius Cope) a synonym of E. coinplicatus, and 

 the very good characters given by Cope for his species should be 

 considered additional characters which clearly define the species 

 E. coniplicatus. 



E. coniplicatus^ as thus understood, seems to be the common 

 species of Pleistocene times in the United States ; its geographi- 

 cal distribution extending over a wide area east of the Rocky 



Fig. 22. E coinplicatus. (Tule Caiion, Texas.) Superior molar-premolar series of right 

 side sectioned toshovv change in teeth due to wear. A , triturating surfaces ; A ^ sections cut 

 parallel to the triturating surface about the middle of the crowns. (No. 10611, Coll. A.M.N.H.). 



Mountains and south over the Gulf States, and perhaps along the 

 Atlantic coast as far north as New Jersey; though the specimens 

 reported from this region cannot be certainly identified, the 

 material consisting only of single teeth. In the collections from 

 the Niobrara River there are a gieat number of jaws, skull frag- 

 ments and bones, which from their size and general characters 

 evidently belong to this species. The specimen represented by PI. 

 XVIII, Fig. B (No. 2725 Am. Mus. Coll.) is typical of the horse 



