Peterson : MrocENE Beds of Nebraska and Wyoming. 57 



Description of New Material. 

 Parahippus nebrascensis sp. nov. 



(Plate XIX.) 



(Type No. 1440, Car. Mus. Cat. Vert. Foss.) 



This species is based on a skull with the left mandible practically 

 complete, the pelvis, the right femur, tibia, calcaneum, astragalus, 

 and the proximal end of a metapodial of one individual. The speci- 

 men was found in the upper Harrison beds on Niobrara River, in 

 Sioux County, Nebraska. 



The remains represent a large species of this genus, and they are 

 different in other respects from forms that have been described. On 

 comparison with a cast of the type (jVP-?) of Parahippus (Anehippus) 

 texanus Leidy, which is in the American Museum of Natural History, 

 it appears that the present species more nearly resembles the type of 

 P. texanus than any other species. The type of the latter represents 

 a smaller animal than the species under consideration, and has the 

 anterior median tubercle larger, and the ridge which connects the 

 median with the internal tubercle more constricted. The postero- 

 internal tubercle of M^ in Parahippus nebrascensis is more highly de- 

 veloped than that in P. texanus. The premolars are of proportion- 

 ately large size when compared with the molars. This is character- 

 istic of the genus. As usual the second premolar is the longest in the 

 series. In Parahippus nebrascensis the protostyle of P- 2 - is unusually 

 well developed and it suggests the European species Anchitherimn 

 aurelianense. 



The true contour of the skull is partially lost on account of lateral 

 crushing. The lachrymal fossa is, however, plainly indicated. It is 

 shallow when compared with that of Hypohippus osborni Gidley. The 

 zygomatic arch is rather light, but the masseteric ridge of the jugal is 

 proportionally more prominent, though shorter than in the recent 

 horse. From the masseteric ridge upward and forward the face is 

 gently concave, leaving no separate malar fossa. The orbit is large ; 

 its anterior border is opposite the anterior part of M^. Posteriorly 

 the orbit is closed. The sagittal crest is well defined, but short. The 

 occipital condyle is of large size and there are large accessory facets 

 on the basi-occipital for the atlas. 



