676 THE BEIDGER EPOCH. 



on wearing. It is more developed in some specimens than others. There 

 are no cingula on these molars excepting a weak one at the external base 

 of the first true molar. The enamel is smooth. 



Measurements superior molars. 



M. 



Length of five molars 0.071 



Length of three posterior molars 0470 



Length of last molar 0159 



Wiilthof last molar 0200 



Width of penultimate molar 0210 



Length of penultimate molar 0168 



The measurements of a mandible of another specimen are rather 

 smaller than those of Leidy's .type. 



Length of five posterior molars 071 



Length of true molars 045 



Diameters third premolar ^'^"**'"''I"'«^*"'"^ ^^^^ 



i transverse . 007 



Diameters of secoml true molar ^■^'^*'^''°P°«*"''"^ "^^ 



( transverse 010 



Depth of ramus at second true molar 028 



The first-named specimen came from Cottonwood Creek, and the sec- 

 ond from Black's Fork of Green River, both in the Bridger Basin. 



Hyrachyus implicatus Cope. 



Paleontologie.ll Bulletin, No. 12. (On some Eocene Mammals, etc.), March 8, 1873, p. 5; Specimen No. 

 2. Annual Report U. S. Geol. Surv., of the Territories, 1872 (1873), p. 605, Spec. No. 2. Hy- 

 racht/us crassidena, Scott, Spier, and Osborne. Paleontological Report Princeton Scientific Ex- 

 pedi., 877, 1878, p. 52. 



Plate LVIII ; figs. G, 7. 



This tapiroid species as now defined is represented by an imperfect skull 

 in my collection. The part preserved is one side of the face with all the 

 superior molar teeth, with the right half of the mandible supporting all the 

 teeth. The superciliary and other orbital borders of the right side are also 

 preserved. The specimen agrees in its proportions, and in all the details, 

 with the description given by Princeton paleontologists of their H. crassidens. 



The superior molar teeth have no external or internal cingula, but the an- 

 terior and posterior are present excejit on the first premolar on the second and 

 third premolars, and where there is no anterior cingulum. The premolars, ex- 

 cept the first, have two uninterrupted cross-crests, the anterior of which is the 

 longer, and curves round the internal extremity of the posterior ; to it in the 

 fourth, and beyond it in the second and tliird. The cross-crests of the true 



