HYRACHYUS, 675 



median (III) is nearly similar to the others in width; in the T. roulini, much 

 larger than the lateral. 



The phalanges of the first cross series are more contracted distally. 



Thus the more important differences between the skeleton of the two 

 species in addition to those pointed out under the head of the genus, are those 

 of the ulna, the scapula, the lumbar vertebrse, the ilium, and the crest of the 

 tibia. The scapula is more like that of Tapirus terrestris, while the ilium 

 is approximated by that of T. malayanus among living species; its form 

 leans toward the Equine series, and not to the Palseotheroid. 



The following measurements of the inferior dental series are derived 

 from the specimen enumerated at the beginning of the description of this 

 species as No. 2 : 



Length of last two superior molars 0.041 



Length of last 019 



Width of last 022 



Length of inferior molar series 095 



Length of premolars 040 



Length of last molar 021 



Width of last molar 013 



Depth of ramus at first true molar 040 



Hyrachyus agrarius Leidy. 



Hayden's Report Geol. Surv. Wyoming, 1871, p. 357. Proceed. Academy Phila., 1871, 229; 1. c. 1872, 

 19, 168 ; Hayden's Report Geol. Surv. Montana, 1872, 361. Hyrachyus agrestis Leidy. Hayden's 

 Report Geol. Surv. Wyoming, 1871, 357. Lophiodon bairdianus Marsh, Amer. Jour. Sci. Arts, 

 1871, II p. 3. Hyrachyus implicatus Cope, Specimen 1, on some Eocene mammals, etc., Paleon- 

 tological Bulletin No. 12, p. 5. 



This species is nearly abundant as the H. eximius, from which it is 

 chiefly distinguished by its inferior size. None of the numerous specimens 

 which I obtained in the Bridger Basin are complete, so that I refer to Leidy 

 for a fuller description than I can furnish. A specimen represented by both 

 maxillary teeth with most of the molars was, with a second and more per- 

 fect specimen from the Washakie Basin, referred by me to a distinct species 

 under the name implicatus. The second specimen represents a different 

 species from the first, which is, I think, an E. agrarius, and I retain for it 

 the new specific name then given. 



In H. agrarius the superior molars have the cingular cusp smaller 

 than the anterior external lobe, and separated from it by a ridge. A ridge 

 or rib projects into the median valley from the external lobe, forming a loop 



