320 Bulletin American Museum of Natural History. [Vol. XXXIV 
of the New Mexican Wasatch, agrees with Cope’s figure and description 
and may serve as topotype. 
The species is larger than H. miticulus, the lower molars more elongate, 
the fourth premolar decidedly larger, longer and more trenchant. The 
hypoconulid and entoconid of m3 are clearly distinct. M2? almost or quite 
as large as m', hypocone distinct, and on m'2 subequal with protocone. 
Deuterocone of p* as wide as protocone, on p® large with strong connecting 
crests. Length of lower molars, mj-3 = 14-15 mm. 
A number of jaws from the upper and lower levels of the New Mexican 
Wasatch agrees very nearly with this species. There would appear to be 
considerable variation in certain characters. In three specimens the last: 
upper molar has the metacone greatly reduced, in the others, asin the topo- 
_ type, it is normal. In the topotype, as in Cope’s type, the metaconid is 
indistinctly twinned, but in other specimens it is simple. 
Hyopsodus lemoinianus Cope does not differ in any way from this species. 
The type is from the Bighorn Wasatch, horizon unknown. Loomis records 
the species as from the Gray Bull River, but all our typical material comes 
from the Lost Cabin horizon, and some if not all of his Gray Bull specimens 
may be from this level, others are perhaps large individuals of miticulus. 
In the Lost Cabin horizon this species is abundant both in the Bighorn 
- basin and in the Wind River Valley. It is represented by the smaller 
mutant lysitensis in the Lysite of both basins. | 
Hyopsodus mentalis lysitensis subsp. nov. 
s 
Hyopsodus lemoinianus Cope OSBORN, 1902, Bull. A. M. N. H., Vol. XVII, p. 183, 
fig. 7a. Not the type specimen of H. lemoinianus. 
Type, No. 15621, left ramus of jaw with pe-m3; Lysite beds, 15 Mile 
Creek, Bighorn basin, Wyo. Exp. 1911. | 
While the typical mentalis appears to be strictly limited to the Lost Cabin 
“Zone, a smaller form is abundant in the Lysite both in the Wind River and 
Bighorn basins. I regard it as a subspecies of mentalis. | 
This subspecies lies intermediate between H. mentalis and H . miticulus, — 
both in size and progressiveness. Although chiefly found in the Lysite, . 
it occurs more sparingly in the Lost Cabin horizon. 
Hyopsodus powellianus Cope 1885. 
Phenacodus zuniensis Corr, 1882, Proe. Amer. Phil. MOOG OV Glo XX, a 
Not P. zuniensis Cope, 1881, | 
