18.<«0.] 44 i [Cope. 



Measurements of Superior Molars. 



MM. 



r anteroposterior 19 



Diameters in. i -^ transverse 18.5 



{_ loagiludinal 26 



r anteroposterior 20 



Diameters m. ii -, transverse 18 



(^ longitudinal 36 



The anterior inner column presents in the second individual the same 

 flattened form as in the first above described, but it is connected with the 

 anterior crescent by a narrow isthmus, and not in two of three teeth at 

 least, where the part is preserved, with the posterior crescent. The ante- 

 rior molar (third premolar from behind) has this junction a complete fu- 

 sion of the two. As one of these teeth is a true molar it is possible that 

 they represent another species. 



The animal last described may possibly belong to a species distinct from 

 the H. retrusum, and perhaps to a species of Protohippus or Hippidium. 

 If so, it diflers from the known species of those genera in the posterior 

 position and flatness of the anterior column. In that case it may be called 

 P. or H. profectus. It approaches nearer to Equus than any known 

 species of those genera. 



Measurements of No. 2. 



MM. 



r anteroposterior 45 



Diuiiieters of p. m. i -| transverse 23 



(^ longitudinal 19 



i anteroposterior 24 



Diameters of m. iii \ transverse 20 



\_ longitudinal 36 



In dimensions this species is then about equal to the H. speciosum. 

 From Phillips county, Kansas, from the Loup Fork bed. Frank Hazard. 



HiPPOTHERIUM PANIENSE CopC. 



Bulletin U. S. Geolog. Survey Terrs. (Hayden), No. 1, 1874, p. 12. An- 

 nual Report U. S. Geolog. Survey Terrs., 1873 (1874), p. 522. 



This species is known from molar teeth from the Loup Fork beds of N. 

 E. Colorado. The enamel borders difler in their degree of complexity ac- 

 cording to the amount of wear to which they have been subjected. 



In the molar which presents the more simple type of enamel borders, 

 the posterior internal column is entirely fused with the posterior inner 

 crescent. The anterior inner column is therefore alone. It is nearly 

 round in section, and presents no angular apex towards the inner cres- 

 cents, and there is only a trace of the loop which is usually directed to- 

 wards it from the enamel border connecting the crescents. The borders 



