1915.] Matthew and Granger, Lower Eocene Wasatch and Wind River Faunas. 29 
Jaw is shorter than in V. gracilis (in which Pi—Me, = 30 mm.; my» = 9.5 
mm.). It is thus intermediate between V. acutus and gracilis, but nearer 
to the latter. Six lower jaws, all from the Lost Cabin horizon in the Wind 
River Basin, are referable here. 
Uintacyon Leidy 1871. 
Type, U. edax from Middle Eocene (Bridger). 
: atic 23.1.4.23 : ‘ 
Generic characters: Dentition 2314.93) D* carnassiform with small parastyle; 
m'~ with moderately extended parastyles, metacones slightly smaller than paracones, 
protocones lacking posterior crest. Lower premolars reduced, posterior accessory 
cusps rudimentary; mi with high trigonid and trenchant heel, m, short with low 
trigonid and small trenchant heel. 
Two distinct species are represented in our Lower Eocene collections. 
One, “ Didymictis”” massetericus Cope is about the size of the Bridger species 
Gan ) No. (623! 
‘ ae A. ™, 
Fig. 24. Uintacyon massetericus, lower jaw, outer view, natural size, and crown and 
outer views of teeth enlarged to two diameters. No. 16231, Almagre beds, Wasatch forma- 
tion, San Juan Basin, New Mexico. 
U. jugulans. The other is about as large as U. vorax Leidy. Both are rare. 
The genus is differentiated from Miacis by the trenchant heels of its lower 
