154 
INSECTIVOKA. 
lower molar with this anterior transverse triangle, a diagonal ridge, and a 
heel with raised border. The fourth premolar has a V-shaped crest on its 
anterior half, the angle being an elevated apex of the external face, the 
limbs descending- inward. 
This genus differs from Ancliippodus and Ecfogamis in the far less 
gliriform character of the incisor teeth, although the composition of the 
molar teeth exhibits a true resemblance to that seen in those genera. The 
incisor is annectant to the form usual in Mammals, betraying the Rodent 
character in the absence of enamel from the posterior face, and the oblique 
bevel posteriorly from the apex to the shank. The ? canine or superior 
incisor (second form) is elongate, and without distinction between crown 
and root, but is straight, and not gliriform. A resemblance to the superior 
incisor of Ectoganus can be observed in the deep emargination of the 
enamel to near the apex on the inner side, and the convexity of the 
opposite side. 
A strong resemblance can be discovered between this genus and 
Tomitlierium, which is described under the Mesodonta. The composition 
of the inferior molars in the latter is essentially the same in the two genera, 
but the anterior cusps and yokes are relatively less developed in TomitJierium. 
An obvious resemblance is seen in^the last premolar, which is somewhat 
sectorial in the form of its anterior half in both genera. There is no 
enlarged external incisor in Tomithermm, but either arrangement is con¬ 
sistent with Mesodont affinities, and even incisors of Rodent-like character, 
in view of the structure of Chiromgs, so that Esthonyx might peihaps be 
properly referred to that group. Its resemblances to Erinaceus are, how¬ 
ever, so many, that I leave it here for the present. 
Esthonyx bisulcatus, Cope. 
Plate xl, figs. 27-33. 
Esthonyx bisulcatus, Cope, Report Vert. Foss. New Mexico, U. S. Geog. Siirvs. W. of 
100th M., 1874, p. 7; Id., Ann. Report U. S. Geog. S’drvs. W. of 100th M., 
1874, p. 118; System. Cat. Vert. Eocene New Mexico, U. S. Geog. Survs. 
W. of 100th M., 1875, p. 24. 
Esthonyx acer, Cope, Report Vert. Foss. New Mexico, U. S. Geog. Survs. W,. of 100th 
M., 1874, p. 7 ; Id., Ann. Report U. S. Geog. Survs. W. of 100th M., 1874, 
p. 119. 
Represented by parts of both mandibular rami, with molar and loose 
incisor teeth of olie individual; a mandibular ramus, siqiporting tlie- last 
