1885.] Eocene Period of North America, 465 
Of the three genera with very large incisor (? canine) teeth, 
Mixodectes has the last lower premolar with a simple cusp. 
There are two species from the Puerco beds, The smaller of 
these, M. pungens Cope (Fig. 9), is about the size of the kit fox. 
Its premolars are of irregular size. In the two other genera the 
fourth premolar has a second cusp on 
the interior side of the principal one. 
Both have the crowns of the inferior 
true molars composed of two triangles 
as in Mixodectes and Pelycodus. In 
Microsyops Leidy, there is but one one- 
rooted premolar. There are three spe- yc. SD cedate depo 
cies from the Wasatch and Bridger beds. Cope, lower jaw right ramus, 
The type is the M. gracilis Marsh (Fig. naturel Sie. Te ee 
26), from the latter. It was a small ani- Report U. S. Geolog. Survey 
mal, not exceeding a gray squirrel in iii 
dimensions, In Cynodontomys the premolar teeth are more 
reduced in size than in any of the allied genera, two of the three 
being one-rooted. The large ? incisor a 
tooth has a correspondingly large devel- 
opment. The species was found by Mr. 
Wortman in the Wasatch beds of the 
Big Horn basin, Wyoming Terr. ee 
The most evident lemuroids yet found A 
in America belong to the family of the CSEE 
Anaptomorphide. But one genus iS Fic. 10.—Cynodontomys lat- 
certainly known to belong to it, Anapto- ond eee a 
morphus Cope. The genus Indrodon’ Wyoming. Fig. a’, from 
resembles it in dental formula excepting sbt oee a ta: 
in the possession of three instead of two nı, F. V. Hayden in charge. 
incisors. It embraces but one species, 7. ma/aris, which was 
found by David Baldwin in the Puerco formation of New 
Mexico. , 
Anaptomorphus was founded on the lower jaw of a small spe- 
cies, A. emulus Cope, which does not exceed that of a ground 
squirrel (Tamias) in size (Fig. 11). It agrees with a very few of the 
living lemurs (Indrisinz) in the number of its teeth, but it differs 
from them all in having short erect incisor teeth as in the higher, 
monkeys. The molar teeth known are a good deal like those of 
1 Proceedings American Philosophical Society, 1883, p. 318. 
VOL. XIX.—NO. V. 30 
