T^NIODONTA. 
163 
thin. An ungual phalange is stout and compressed, and but little curved, 
and without the basal sheath seen in the Carnivora and some Edentata. 
The exact homologies of the seven mandibular teeth are obscure, and 
% 
it is uncertain to how many the expression molar should apply. The two 
immediately following the incisor differ in form from the last five. 
The symphysis is solid and short; it projects wedge-like between the 
large incisors, whose anterior borders are closely , approximated. There is 
a large mental foramen. 
The typical species is the C. arcamoenus. 
Calamodon arcamoenus, Cope. 
Plates xli, figs. 13-17; xlii, figs. 1-5; xliv, fig. 1. 
Report Vert. Foss. New Mexico, U. S. Geog. Survs. W. of 100th M., 1874, p. 6; Id., Ann. 
Report U. S. Geog. Survs. W. of 100th M., 1874, p. 117. 
This species is represented primarily by a left mandibular ramus con¬ 
taining a part of the incisor tooth, with which were found portions of the 
other ramus, with fragments of incisors, and two molars with entire crowns. 
These remains were all found in immediate association, and evidently belong 
to a single individual. To this species, I refer inferior incisors, with a few 
associated bones, of three other individuals. 
The mandibular ramus is stout in all its dimensions, and the 
symphysis is completely co-ossified. The base of the coronoid process 
is thickened anteriorly, and the ascending portion forms an ascending 
ridge, but the masseteric fossa is not defined below nor antero-inferiorly. 
The inferior border of the ramus is inflected neither inward nor outward, 
as far back as preserved, i. e., the line of the condyle. The external 
face of the ramus is convex, and the thickness of the ramus dimin¬ 
ishes very little anteriorly. It is fractured near the middle, but the 
alveoli for seven teeth behind the incisor are preserved. Of these, the 
last five are quite similar in proportions, while the first two are of charac¬ 
teristic forms. How many of them should be regarded as molars, and how 
many, if any, canine and incisors, the material is not sufficiently complete 
to enable me to determine. The posterior two alveoli are subquadrate, 
with rounded angles; the three preceding them are more nearly round 
