94 
CREODONTA. 
As compared with the Synoplotlieriiim lanitis^ Cope, to Avhich this species 
is probably allied, all the teeth are wider and more robust, excepting the 
canines. Although the disposition of the tubercles of the lower molars in 
Sijnoplotlierium is unknown, the narrow form of their bases renders it prob¬ 
able that the structure is rather as in HycEnodon than as in Amhloctonus, 
especially in regard to the antepenultimate, which is so excejDtionally tuber¬ 
cular in the present animal. 
PACHY^NA, Cope. 
Report Vert. Foss. New Mexico, U. S. Geog. Survs. W. of 100th M., 1874, p. 13j Id. 
Ann. Report U. S. Geog. Survs. VV. of 100th M., 1874, p. 125. 
Established on a single superior molar tooth of a large Carnivore, 
apparently allied to the group of flat-clawed Carnivora. It is either the 
last premolar or first true molar. It is characterized by the absence of the 
cutting-edge seen in the allied genera, and its replacement by a conic 
tubercle. 
The crown supports three principal tubercles, two external and one 
internal. Of the two external, the anterior is the largest and most promi¬ 
nent, and it is separated from the posterior one by a deep notch. The 
internal tubercle is opposite the anterior external, from which it is separated 
to the base by a deep notch. The sections of the tubercles are subround. 
Thus the principal lobe is a cone, and the inner one a perfect cone, a 
little less elevated than the principal one. 
The affinities of this curious genus are not yet determined. 
Pachyaena ossifraga. Cope. 
PJate xsxix, fig. 10. 
Report, loc. cit., p. 13. 
Report, loc. cit., p. 125. 
CroAvn with Avell-deA'eloped anterior and posterior basal tubercles, Avhich 
resemble the short heels of some inferior teeth; no cingula, either internal 
or external. The external cones exhibit an obtuse anterior and posterior 
cutting-ridge, but there is none on the internal cone. Enamel slightly 
rugose. 
