COPE.] PALEONTOLOGY LOUP FORK EPOCH. 531 



cles, nor columns, and the cement-deposit in the lakes is very small. 

 The third premolar and first molar are about as broad as long. 



Measurements of the upper jaw. 



M. 



Length of true molars 0.03T 



Length of last molar, (outside) - 036 



Width of last molar, (anterior column) 016 



Length of first molar 0*20 



Width of first molar 019 



Length of last premolar 014 



Width of last premolar 013 



Length from first premolar to canine 016 



Length from first premolar to third incisor 036 



Length from third incisor to end of premaxillary 03d 



Measurements of the lower jaio. 



M. 



Length from apex of third incisor to end of third premolar . . 0.120 



Length from apex of third incisor to second premolar 698 



Length from apex of third incisor to first premolar 059 



Length from apex of third incisor to canine 025 



Depth at third premolar 040 



Depth at canine 041 



From the heads of Pawnee Creek, Colorado. 



Peocamelus occrDENTALis, Leldy, Anc. Fauna Dak. and Neb., 151. 



Specimens in fine preservation, but referred, with some doubt, as 

 above. The dimensions of the teeth are intermediate between those of 

 the species above named and the P. gracilis^ Leidy. 



MERYCODUS, Leidy. 



Meetcodus qemmifee, Cope, loc. cit, 22. 



A small ruminant, represented by jaws and teeth of three individuals 

 found in association with the species above described by the writer. 

 These embrace only the true molar-teeth in good preservation. They 

 resemble thoSe of M. necatus, Leidy, in form and size, but differ in hav- 

 ing a rudimental column between the principal columns at their bases, 

 a character which I have satisfied myself does not exist in the Isfiobrara 

 specimens described by Dr. Leidy by autopsy. These only appear on 

 the grinding faces after prolonged attrition. First molar equal to the 

 last premolar in antero-posterior diameter. 



Measurements. 



M. 



Length of four posterior molars 0.0";7 



Length of true molars 030 



Length of second molar 090 



Width of second molar - 040 



Length of third molar - -- Olii 



Width of third molar 006 



Depth of jaw at second molar 015 



PEOBOSCIDIA. 

 MASTODO:tf, Cuv. 

 Mastodon peoavus. Cope, Synop. Vert. Col., 1873, 10.. 



Eepresented by an entire anterior molar, portions of posterior molars, 

 and an astragalus, all found associated by the writer. They probably 

 pertain to the same individual. 



