FOSSIL HORSE REMAINS FROM IDAHO — GAZIN 



303 



The entoconid and adjoining hypoconulid are simple and rounded 

 in moderate wear, with no significant features to distinguish them in 

 the fossil form. 



On the outer surface the external walls of the protoconid and 

 hypoconid appear more convex in many of the specimens than in 

 E. grevyi or E. caballus, although in some dentitions flattening is 

 noticeable. The reentrant between the columns is shallow and acute 

 in the premolars though deeper and more open in the molars. The 



ft 



Figure 22.— Plesippus shoshonensis Oidley. Enamel patterns of left lower cheek teeth 

 in seven selected individuals arranged according to age. In the first two dentitions the 

 premolars are deciduous. U.S.N.M. nos. (from top to bottom) 12560, 12785, 12776, 12790, 

 12553, 12504, and 12546. One-half natural size. Hagerman lake beds, upper Pliocene, 

 Idaho. 



