TRANSACTIONS OF WAGNER 

 60 



UINTA SELENODONTS 



Metacarpal v. is like the second, except that it has a narrower proximal 

 end and a more strongly curved shaft. In correspondence with its larger size, 

 this bone has a more extended contact with the unciform than in Protylopiis. 



A single phalanx, the proximal one of the fourth digit, is preserved in 

 connection with the manus; it has the same general shape as in Protylopus, but 

 is depressed and very slender. 



The pelvis (No. 1 1,223), so far as it is preserved, is tylopodan in character 

 and recalls that of Lcptomeryx. The anterior portion of the ilium is broken, 

 so that its length cannot be determined, but it may be seen that the plate- 

 like expansion is broad and widens suddenly from the peduncle ; the latter 

 is rather short and stout, having a considerable vertical diameter ; the pubic 

 and acetabular borders are obscurely marked, and the iliac surface is narrow. 

 The ischium is relatively quite long, a marked difference from Pocbrotherium, 

 in which this element is much shortened ; it is, for the most part, narrow 

 and compressed, but rather deep dorso-ventrally and sub-trihedral in section ; 

 the dorsal border forms a thin and prominent crest above and for some dis- 

 tance behind the acetabulum, drooping suddenly at the ischiadic notch. The 

 hinder part of the ischium is expanded, depressed, everted, and plate-like; no 

 tuberosity is preserved, but one may, nevertheless, have been present. The 

 acetabulum is large and deep and has very prominent borders, which project 

 far out from the sides of the pelvis. The pelvis of Protylopus, so far as it is 

 known, is similar to that of the present genus, but has a little more the aspect 

 of the innominate bone in Pocbrothcruun , while Leptorcodon agrees somewhat 

 more closely with Lcptomeryx in this regard, though the four genera are very 

 much alike, so far as the pelvis is concerned. 



Of the femur (No. 11,223) the proximal end is lost. The shaft is rel- 

 atively quite long and stout, especially in the antero-posterior dimension, and 

 is well arched forward. This arching is, however, less marked than in the 

 White River genera, Poebrotherhiin and Lcptomeryx, but more than in the con- 

 temporary Protylopus. As in all the genera mentioned, there is a pit above 

 the external condyle for the insertion of the plantaris muscle, a feature which 

 is absent in the modern Camelidce, though in Pocbrotherium it is deeper and 

 larger than in the Uinta genera. The rotular trochlea is narrow but promi- 

 nent, and is deeply grooved. The condyles are rather small and narrow and 

 of almost equal size ; they are larger than in Protylopiis and extend farther 

 behind the plane of the shaft, making the entire distal end thicker than in that 

 genus, for both condyles and trochlea are more prominent. 



