CORYPHODOK 
207 
last molar. The posterior transverse crest of this tooth is low, and sends a 
well-marked oblique ridge to the anterior crest. A cingulum projects from 
the posterior base of the crown, which is not prominent, and disappears at 
the base of the inner end of the transverse crest. Just external to and in 
front of this extremity, a prominent conic tubercle is directed upward and 
inward. This process is not seen in any other of the numerous jaws and 
teeth in my possession. Between it and the anterior crest is a low rugose 
tuberosity, representing a cingulum. There is also a cingulum between the 
crests on the external side of the crown. The posterior transverse crest is 
quite oblique, its inner end falling behind the line of the internal cusp. The 
enamel, where not worn by attrition, is marked by linear rugosities. 
Measurements. 
M. 
Width of the molar behind. 0.023 
Elevation of the cusp from base of the crown. 0.010 
Elevation of the posterior crest at the middle (half worn). 0. 010 
The Coryphodon cuspidatus was about the size of the C. simus. In its 
characters, it marks an extreme position in the genus, in its internal cusps 
and lateral cingula. Remote approximations to the former peculiarity are 
seen in the 0. oUiquus and C. Jobatus, in the presence of a low crest or flat 
tubercle in the same situation. The C. lohatus differs especially in the 
absence of lateral cingula, large heel, and much larger size. 
Coryphodon obliquus. Cope. 
Plate xlvii, figs. 1-7. 
This species is represented by the greater part of the left ramus of the 
mandible, and a portion of the right one, with the last two molars and a 
canine tooth. These pieces are of robust proportions, and present various 
specific characters. 
The mandibular ramus is of small vertical and of considerable trans¬ 
verse diameter. It is deepest below the last molar, the depth gradually 
diminishing anteriorly, and more rapidly posterior to that point, where the 
inferior border is concave upward. This is quite different from the form of 
the ramus in C. radians^ where the vertical diameter is greatest at the last 
premolar and least at the last true molar, and where the inferior border is 
