Cope.] lo [May 16, 



These molars are covered with a layer of cementum, which is included 

 in the measurements. 



The mandible, I am disposed to refer to a smaller variety of this species 

 for the present. The well-worn fourth inferior premolar indicates that it 

 could not belong to the genus Eschatius, where tliere is no opposing tooth 

 in the superior series capable of producing such a result. The hook be- 

 low the condyle is well developed in this jaw. The incisor teeth are 

 narrow. The canine is small and is separated from the incisors by a dias- 

 tema. The triturating surface of the fourth premolar is triangular, and 

 includes a lake. The molars increase in size posteriorly. The mental 

 foramen is large, and is situated behind a point below the canine. 



Measu7'e7nents. M. 



Length of jaw from incisive alveoli to angle 415 



Height at coronoid i:»rocess 290 



" at condyle 218 



" ramus at M. i 070 



" " " middle of diastema 040 



Length of symphysis 09G 



" from base of incisors to canine 043 



" " canine to P-m. iv 092 



" of all the molars 147 



Diameters P-m. iv / anteroposterior 022 



•- transverse 013 



Diameters M. i j anteroposterior 035 



c transverse 019 



Diameters M. ii {anteroposterior 042 



I transverse 019 



Diameters M. iii /anteroposterior 048 



I transverse 016 



From Tequixquiac. 



A cannon bone in Condon's collection, which may belong to this species, 

 measures fifteen and a quarter inches in length. So far as the evidence 

 goes it may as well have belonged to the Escliatius conidens. According 

 to Leidy the cannon bone of the AucJienia californica Leidy measures 

 nineteen inches in length. A cannon bone of at least this size, with other 

 bones of the skeleton, occurs in the museum of the School of Mines, and 

 may belong to the Californian species. Whether that species is a true 

 Auchenia or not remains uncertain, as the teeth are unknown. 



ESCHATIUS, gen. nov. 



This genus is well characterized hj the reduction of the fourth superior 

 premolar to a simple cone, in place of the usual double crescent charac- 

 teristic of the Ruminantia generally. This is the greatest known reduc- 

 tion of the premolar series in the Ruminantia, exceeding anything in the 

 BovidsB, a family otherwise more specialized than the Camelidse. If my 



