I04 Bulletin American Museum of Natural History. [Vol. X, 



Of the bones of the hind foot, the entire tarsus is preserve^i 

 with the exception of the cuneiform. These parts of the skele- 

 ton present a most striking resemblance to those of Focbrothe- 

 riu7n in all the details of their structure, the only difference 

 discoverable being that of size. The third metatarsal is present 

 but unfortunately a small part of the shaft is missing so as not 

 to exhibit its full length ; there is enough, however, to indicate 

 that it was unusually long and slender, much flattened upon the sur- 

 face which it offered to the second metatarsal, and that th'e form of 

 the shaft, moreover, had that peculiar squarish outline upon cross 

 section, a feature so highly characteristic of the Oligocene 

 Cameloids. Another distinctive cameloid feature is seen in the 

 increased size of the medullary cavity. The lateral or fifth meta- 

 podial was reduced to a mere splint, as is indicated by the much- 

 reduced facet upon the cuboid ; this facet is relatively as small 

 as it is in the cuboid of Poebrotherium. The phalanges have 

 about the same proportions and shape as the corresponding 

 bones of the White River species. 



That Paraineryx {Leptotrao^uliis) was a member of the Tylo- 

 poda, as has already been pointed out by Marsh and Scott, there 

 can be very little doubt, but at the same time the evidence is 

 equally conclusive that it does not stand in direct ancestral line 

 with the succeeding Poebrotheres. The evidence against such a 

 conclusion is to be found in the fact that Paranieryx {Leptotraga- 

 lus) has only three premolars in the lower jaw, an enlarged canini- 

 form canine and relatively short, thick inferior premolars, the 

 last of which, or fourth, has a considerable development of the 

 internal cusp. It may therefore be looked upon as a precociously 

 specialized side branch which died out at the close of the Eocene 

 and left no modified descendants. 



Protylopus petersoni,' gen. et spec. nov. 



This genus and species is ])rimarily founded upon the anterior 

 portion of a skull from which the left ramus is missing. The 

 specimen is broken obliquely in such a manner as to show upon 

 the right side all of the facial portion, including the orbit and the 



1 This species is named in honor of Mr. O. A. Peterson, whose explorations of the Uinta 

 Beds have been attended with such marked success. 



