TRANSACTIONS OF WAGNER 



So 



UINTA SELENODONTS 



short, narrow transversely, and thin in the dorso-plantar dimension, much as 

 in Leptomeryx, except that in the latter genus the tuber is distinctly elongate. 

 Upon the external side of the calcaneum, and running for most of its length, 

 is a very conspicuous sulcus, broad and deep ; this sulcus is most marked in 

 Protylopus, less so in Leptoreodon, and still less in Camclomcryx, while in 

 Leptomeryx it is obsolete, only a slight remnant of it indicating that this 

 genus was probably derived from an ancestor which possessed it. The 

 fibular facet is narrow and does not rise so high as in Protylopus or Lep- 

 toreodon, but is more prominent than in Leptomeryx. The distal end of the 

 calcaneum is like that of the latter genus in having a considerable dorso- 

 plantar diameter, this diameter being 'suddenly diminished just above the 

 fibular facet, as it is not in either Leptoreodon or Protylopus. The cuboid 

 facet is relatively broader, but less extended planto-dorsally than in the last- 

 named genus, in which the facet is so warped that its plantar portion presents 

 inwardly rather than distally, while in Camelomeryx this warping is much less 

 in degree. From Leptomeryx the chief difference lies in the relative width of 

 the facet, the astragalus not taking up so much of the cuboid as in the White 

 River genus. The sustentaculum is much more prominent than in the oreo- 

 donts. 



The cuboid is rather small, narrow, and light. The proximal end is 

 divided almost equally between the facets for the calcaneum and astragalus, 

 though the former is perhaps slightly the broader of the two, but not so 

 much so as in Protylopus or Leptoreodon, while in Leptomeryx the astragalar 

 surface is distinctly the broader one. The facets are shaped much as in 

 Protylopus, except that the cuboidal one is less warped and projects less 

 towards the fibular side. The plantar hook is quite large and heavy, but 

 far less so than in the last-named genus or even than in Leptoreodon, though 

 larger and heavier than in Leptomeryx. The distal end is entirely occupied 

 by the large facet for the fourth metatarsal, which is plane in front, concave 

 behind. It is doubtful whether any facet for the fifth metatarsal is present; 

 if so, it is exceedingly small. In Leptomeryx the cuboid is coossified with 

 the navicular, a feature which, like the anchylosis of the trapezoid and mag- 

 num, is very exceptional among the Tylopoda and has not been observed in 

 any Uinta genus. 



The metatarsus consists of a large median pair and a very reduced lateral 

 pair, but as the latter are not preserved in connection with the specimen, it is 

 quite uncertain whether they were retained in their entire length or only 



