TRANSACTIONS OF WAGNER 

 82 



UINTA SELENODONTS 



trochlea is narrow and quite deeply concave; the body of the bone is elongate 

 and very narrow, and the distal trochlea is almost confined to the plantar face. 

 The second phalanx is very much shorter than the first and even more slender; 

 its distal trochlea is reflected well over upon the dorsal face. The ungual is 

 long, narrow, straight, and pointed. The phalanges of Leptomeryx are of simi- 

 lar type, but a little shorter and thicker proportionately. 



The Phylogenetic Position of Camelomeryx. 



The problem concerning the taxonomic position of this genus is rendered 

 somewhat obscure by the incompleteness of our knowledge of it; the mandi- 

 ble and the inferior dentition are quite unknown, and the limbs and feet have 

 not yet been certainly identified, though there is every reason to believe that 

 the specimen above described represents very nearly the actual structure of 

 the genus. From the foregoing description it will be sufficiently obvious that 

 Cameloineryx is very closely allied to Leptoreodon, so much so that one can- 

 not but feel some doubt as to the propriety of separating them generically, 

 though if we may assume that the feet described in this and the preceding 

 section have been correctly referred, the difference is enough for generic dis- 

 tinction. It is a significant fact that almost all the minor differences which 

 separate Cameloineryx from Leptoreodon are structural features in which the 

 former agrees with Leptomeryx, and suggest that the latter was derived from 

 it. There are, however, some objections to this view. In the first place, the 

 ulna and radius — which in the White River genus are separate — are already 

 coossified in the Uinta form. This may be merely individual and due to 

 advanced age, or it may be specific, occurring only in C. longiceps, and again 

 the specimen may perhaps be properly referable to some other genus. But 

 if future research shall show that Camelomeiyx is characterized by anchylosis 

 of the fore-arm bones, it will undoubtedly militate against the conclusion that 

 Leptomeryx was descended from it. Secondly, Leptomeryx is remarkable for 

 the character of its carpus, the magnum having shifted from beneath the 

 lunar, which rests entirely upon the unciform. We might reasonably expect 

 to find in the Uinta ancestor of this genus some indication of this displace- 

 ment, if only in the incipient stage, but in the carpus referred to Camelomeryx 

 there is no such indication. 



Whether Camelomeryx be the direct ancestor of Leptomeryx or not, it is 

 highly probable that it very closely resembles that ancestor in all save a few 



