

nsro. ii- 



ON TWO NEW PERISSODACTYLES FROM THE BRIDGER 

 EOCENE. 



By Edward D. Cope. 



LlMNOHYUS LiEVIDENS. Cope. 



This species is one of the larger forms of the group originally repre- 

 sented by Palceosyops, and which has turned out to be so numerous in 

 species. Thanks to the labors of Prof. Marsh, these have been placed on 

 a recognizable footing, and I have been enabled to distinguish not only 

 the species he has described but a few others in the collections obtained 

 by Dr. Hayden's expedition of 1872. 



The present species is chiefly represented by a nearly complete cranium 

 with dentition, from Bitter Creek, and a cranium lacking the posterior part 

 of one side and the lower jaw, from Cottonwood Creek. The molars have 

 the general form of those of L. robustus, but the second superior premolar 

 has but one outer tubercle. The cingula are much less developed than 

 in that species ; those between the inner cones of the molars being entirely 

 absent. These cones are low, and with the rest of the crowns of all 

 the teeth, covered with smooth and shining enamel. The anterior me- 

 dian small tubercle of the first true molar is wanting. The last true 

 molar has but one interior cone. 



The canine tooth is powerful and bear-like ; the outer incisor is the 

 largest. The premaxillary bones are short, and the side of the face eleva- 

 ted and plane to the convex nasal bones. Zygomatic arch massive. 



M. 



Length molar series (No. 1) 0.140 



" true molars 085 



" three incisors 034 



" crown canine 030 



" " lastmolar. 039 



Width " " ". 036 



Length cranium to occipital crest 345 



" true molars (No. 2) 101 



" last " " (oblique) 030 



Width " " " (transverse) 038 



The measurements of this species are intermediate between those of 

 Palceosyops paludosus and P. major, ofLeidy; those of the latter agreeing 

 with the Limnohyus robustus, Marsh, and perhaps other species. 



Palceosyops fontinalis. Cope. 

 A small species agreeing with the P. paludosus in the two interior 

 cones of the last superior molar. It is represented especially by a con- 

 siderable part of the cranium of an individual in which the last superior 

 molar is not quite protruded, but with the other molars and last pre- 

 molar of the permanent dentition in place. The enamel of these teeth 

 is in accordance with the age, delicately rugose, and while the cingulum 



