1915.] Matthew and Granger, Lower Eocene Wasatch and Wind River Faunas. 445 
No. 4735, upper jaw, 4736, 15603, 12736 lower jaws, and other more 
fragmentary specimens are referable to this species. All are from the Lost 
Cabin horizon in the Wind River basin. | 
Famity TARSIIDA. 
The revision of the so-called Anaptomorphide of the Lower Eocene is 
exceptionally difficult. They are all of minute size, the material is mostly 
very fragmentary, and comparatively scarce, and the number and diversity 
of genera and species appears to have been very considerable. Except for 
a skull, Amer. Mus. No. 4194, found by Wortman in the Bighorn basin 
and referred by Cope to Anaptomorphus, they are known only from upper 
Fig. 19. Notharctus nunienus, lower jaw, outer view and crown view of teeth. Lost 
Cabin beds, Wind River basin, Wyoming. 
and lower jaws more or less fragmentary. The Middle Eocene genera, 
although not quite so rare, are also known only from upper and lower jaws. 
No skeleton parts have been found associated. Various isolated skeleton 
bones of Tarsiid type, and a part of a skeleton from the Upper Bridger 
probably referable to Hemiacodon, confirm to some extent the reference 
to the Tarsiide based upon the characters of the above mentioned skull 
and the general resemblances in dentition. But the affinities and inter- 
relationship of most of the genera placed under this family must remain 
somewhat provisional. The Middle Eocene genera and species of this 
family were very ably and thoroughly revised by Dr. Wortman in 1904, 
upon the basis of the Yale collection from the Bridger formation. Our 
additional and somewhat more complete material from this formation has 
made it necessary, however, to modify some of his conclusions. It appeared 
advisable therefore to include the Middle Eocene genera in this revision. 
