Peterson: Material Discovered in Uinta Basin. 87 



the humerus is not unlike that in Prolorcodon or the oreodonts in 

 general. The olecranon process of the ulna is short and stout, but 

 has apparently a smaller antero-posterior diameter and a less decided 

 tendinal groove than is usual in the oreodonts of the Oligocene. 



Fragments of the hind limb present no noteworthy differences from 

 corresponding parts in Protoreodon or the later oreodonts {Merycoi- 

 dodon). Proportionally the distal end of the femur has possibly 

 a somewhat greater transverse diameter than in the Oligocene oreo- 

 donts and the rotular trochlea is shallower and broader. The head 

 of the tibia is broad, corresponding to the distal end of the femur. 

 The patella appears to have a greater dorsal convexity, or greater 

 antero-posterior diameter, than that bone as described by Professor- 

 Scott. At the same time it is possibly flatter than is usually the 

 case in most oreodonts. 



In the type of Protagriochcerus the astragalus is represented only 

 by the upper half, while in the present specimen the bone is very nearly 

 complete.*'^ Though the bone is typically that of the oreodonts it is 

 at once recognizable by its narrowness and greater height. This 

 feature is apparently characteristic of all the known Uinta oreodonts. 

 In Protagriochcerus and also in Protoreodon the cuboid facet of the 

 astragalus is not concave from side to side as in Merycoidodon, but is 

 practically flat, even more so than in Agriochcerus. On the other 

 hand the posterior extent of the navicular facet of the astragalus in the 

 latter genus reaches proportionally higher up on the posterior face of 

 the astragalus than in Protagriochcerus. The bone as a whole is of 

 quite different proportions in the two genera. 



With the exception of the proportionally greater length of the 

 metatarsals in the present genus they are so similar to those in Mery- 

 coidodon culbertsoni that a general description would fit in either case. 

 The phalanges are also proportionally longer than in Merycoidodon, 

 but otherwise quite similar. The ungual phalanges are slightly 

 narrower and higher than those in Merycoidodon. So far as one may 

 judge from the fragmentary material of the limb-structure of this 

 specimen the high and narrow unguals appear to be the only parts 

 which show ancestral features leading to the characteristic high and 

 compressed terminal phalanges of Agriochcerus. On the other hand 



*8 The astragalus of Protagriochcerus anneclens of the Carnegie Museum collection 

 fits admirably well on the navicular of the type specimen in the American Museum 

 of Natural Historj'. 



