AMBLYPODA. 
179 
Phenacodus sulcatus, Cope. 
Plate xlv% lig. 7. 
Report Vert. Foss. New Mexico, U. S. Geog. Survs. W. of 100th M., 1874, p. 11; Id., 
Ann. Report U. S. Geog. Survs. W. of 100th M., 1874, p. 123. 
Represented especially by the molar tooth corresponding to that above 
described, under the head of P. omnivorus, in good preservation. It is a 
species considerably less than half the size of the one just named, and pre¬ 
sents several imjDortant differences of structure. Of the two outer tubercles, 
one is very small, and there is a third adjacent to the larger, produced by 
the posterior enlargement of the cingulum. As in P. omnivorus, the cingu¬ 
lum extends entirely round the remainder of the crown, and is tubercular 
on the anterior side, or that of the least outer tubercle. The inner tubercle 
is connected with the larger outer by an intermediate one of elongate form, 
so that the series when worn down resembles the transverse ridge of the 
superior molar of HyracotJierium, and which is separated by a groove from 
the cingular ridge on each side. 
Measurements. 
M. 
Transverse diameter ..... .. 0. 008 
Longitudinal diameter. 0. 000 
Distance between the apices of the inner and the outer tubercles .. 0. 004 
Elevation of the cingulum.. 0. 002 
Elevation of the outer cusp... 0.003 
Size similar to that of the corresponding tooth of a Coati. 
AMBLYPODA. 
Cope, System. Cat. Vert. Eocene New Mexico, U. S. Geog. Survs. W. of 100th M., 1875, 
p. 28. 
Mammalia with small (? smooth) cerebral hemispheres, which leave the 
olfactory lobes and the cerebellum exposed. The feet short and plantigrade, 
with numerous (in the known genera five) digits, terminating in flat hoof- 
bearing ungual phalanges. The seven bones of the carpus distinct; the 
unciform articulating- with the lunar as well as with the cuneiform. The 
astragalus flat, without trochlear surface, and attached to the tibia with little 
freedom of movement; its distal extremity divided into two facets, one for 
the navicular, and more or less of the other for the cuboid bone. Molars 
