Cc 
1877.] 219 eeEe 
Descriptions of New Vertebrata from the Upper Tertiary Formutions of the 
West. 
By E. D. Core. 
(Read before the American Philosophical Society, December 21, 1877. 
PITHECISTES BREVIFACIES gen. et spec. nov. 
Char. gen. These are chiefly known from a mandible which supports the 
dentition of one side and part of the other. The dental formula is I. 1 ; 
C.1;Pm.3;M. 3. The single incisor of each side is weak and easily lost, 
and there is on one side only, a small alveolus for a minute second incisor. 
It is therefore probable that in some individuals the incisive formula is 2. 
The canine is not large, and closes in front of the superior canine in the 
usual manner. The first and second premolars are one-rooted, and their 
crowns are wider than long. That of the third premolar is robust, but 
longer. The molars increase rapidly in size, and are not prismatic, but 
are well rooted. They are worn in the specimen, but their structure is 
probably shallow selenodont. The last molar has a long heel or fifth lobe. 
Char. specif. The mandibular ramus is very deep posteriorly, and the 
incisive border is not prominent. The canine tooth is quite small, its trans- 
verse diameter being less than that of the first premolar, and equaling it 
antero-posteriorly. The exterior incisor is weak, and the crown expanded 
transversely, and obtuse. The crown of the first premolar is worn deeply 
by the superior canine. The transverse diameter at the base of the crown 
exceeds the antero-posterior. The crown of the second is wider than long, 
and of the third longer than wide. The molars increase rapidly in size 
posteriorly, so that the length of the third equals that of the three premolars 
plus the canine. The heel is long, and is connected with the remainder 
of the crown by a narrow plate, or in section, an isthmus. There are no 
cingula, but an accumulation at the bases of some of the teeth resembles 
the deposit of ‘‘tartar.’’ The symplysis is very robust, and its upper sur- 
face is marked on each side by a low longitudinal swelling. The opposite 
premolar series are slightly convergent. 
The form of the mandible of this animal, as well as the number and pro- 
portions of the teeth, curiously resemble that of the corresponding part of a 
monkey. The species was about the size of a red fox. 
Measurements. M. 
Length of ramus from heelof molar III................ .057 
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