206 0. C. Marsh—New Tertiary Mammals. 
therium tyrannus Marsh, and may be divided as follows: In- 
cisors 2-2, canines 1-1, molar series 7-7. There are ache 
sath, also, in the upper jaw behind the canine. The first pre- 
molar above and below has only a single fang. The upper 
molars have an alien pare of pointed cusps, and on the i inner 
Measurements. 
Longitudinal extent of upper molar series, ...........05+ 26; ae 
Eettent of three upper true molaray 6 cisiaeses ag s'ch bso 43 155 
Extent of three lower true molars,..........e0seeese0es 18 
Antero-posterigr diameter of last lower molar, Rr eee 6°6 
Transverse iameter, ht ea ee ee ie wks Cees 5 is ks eS 4° 
Depth of jaw on posterior face below last lower molar,...10° 
This species is represented in the Yale Museum by the ge 
important part of several skeletons, which were found, last au- 
tumn, by Mr. J. F. Quigley, Mr. G. G. Lobdell, Jr., and the 
writer, in the Tertiary deposits of Western Wyoming 
— crassus, gen. et nov. 
in the proportions of the Boe they : are very  wailar The 
present species was about as large as a raccoon, but the lower 
jaws are much stouter, and are ankylosed at the symphysis. 
Measurements. 
Longitudinal extent of lower molar series,.......-  weukisn ee 
Extent of three lower true molars, ........ s..eeeeceees 23°5 
Antero-posterior diameter of last lower mae: PE a 
Transverse diameter, ....<..++..+++ whan 4s oe . ky eek 5'5 
Extent of last three upper mo molars, PO EBITD | 2 
Transverse diameter of last upper ‘molar, Be Ye ee Ts 7'8 
The specimen on which the above description is mainly based 
was discovered, last September, near Henry’s Fork, Wyoming, 
by Mr. O. Harger, of the Yale party. 
