32 



E. L. Troxell — Horned Eocene Ungulates. 



"In its cranial characters and dentition, this genus resembles 

 most nearly Hyrachyus Leidy, and Helaletes Marsh. It differs 

 especially from these genera, so far as they are known, in the 

 presence of a pair of dermal horns on the nasal bones, which were 

 strengthened to support them. These horns were placed opposite 

 each other, and their position, in a nearly perfect skull in the 

 Yale Mnseum, is indicated by two rugosities, which have their 

 surfaces marked by radiating lines. In the present species, 

 which was about as large as a sheep, the horns were widely 

 divergent. 



110 82 TYPE 

 Y. P M 



Measurements. 



mm. 



Space occupied by seven teeth in upper molar series 77 



Extent of three true molars 41 



Distance between orbits 62 



Distance between apices of horn rugosities 27 



Length of frontals on median suture . 62 



Expanse of occipital condyles 40 



"The remains of this species at present known are from the 

 Eocene of Wyoming. ' ' 



So far as one may judge from the teeth, the species 

 here described by Marsh is very close to Hyrachyus 

 affinis. There are slight variations in the form of the 

 third npper molar, but the premolars are of the typical 

 Hyrachyus sort, with the strong anterior cross crests, 

 the protoloph, enveloping the thin short metaloph which 

 lies transversely across the center of the tooth. 



These contrasts may be made : 



