0. C. Marsh—New Tertiary Mammals. 125 
On the last lower molar it extends entirely around the posterior 
obe. The first of the upper true molars has the two inner 
cones nearly of the same size. The small intermediate median 
tubercles are well developed on the upper molars, and all the 
teeth are strongly rugose, even in fully adult animals. The 
nasal bones contract anteriorly and are rounded in front. The 
ic 
unite by a very short median suture, similar to that in Paleo- 
Measurements. 
Antero-posterior extent of last three upper molars, La 
Antero-posterior diameter of last upper molar, 41° 
Transverse diameter, ee ar en ae a ee 43°5 
Antero-posterior diameter of last upper premolar, - ------ 20° 
peveversé diameter, .__..._..._..... i teases 26°5 
Antero- osterior diameter of last lower molar, 
Vertica diameter of zygomatic process of squamosal,.... 34° 
The specimen on which the above description is chiefly 
based was discovered, in September last, by Mr. F. Mead, Jr., 
hear Henry’s Fork, Wyoming. Other specimens of the same 
nr, Mr. G. M. 
8eological formation was lower Miocene, or Hocene. 
Hyrachyus princeps, sp. NOV. 
This well-marked species includes the largest of the Tapiridee 
yet found in this country. The remains representing it indi- 
cate an animal nearly three times the bulk of Lophiodon Baird- 
us Marsh, and probably twice that of the individual named 
yrachyus eximius by Dr. Leidy. The specimens on which the 
Species is based consist of a nearly complete series of upper teeth, 
and several lower molars, with the more important parts of the 
skeleton, all ertaining to one animal, and remarkably well 
Preserved. The last two upper molars are unusually lar 
ede to the rest of the series, and have as antero-external 
quite separate, and with its apex incurv 
Measurements. 
Ettent of entire upper molar series, 194°. mm 
<tent of upper true molar series, . - -- - ------- -------- 76° 
Tra ro-posterior diameter of last upper molar, - 21°2 
emee Cintneke 2 ee st a eae 
eet, = : oF: 
ro-posterior diameter of penultimate lower molar, - - 28°75 
Transverse diameter, ~ 17 
