TRANSACTIONS OF WAGNER 

 104 



UINTA SELENODONTS 



versely it is quite narrow and compressed ; the masseteric ridge and surface 

 are well marked, though somewhat less prominent than in Agriochcerus. The 

 vertical depth of the jugal gives to the lower rim of the orbit considerable 

 elevation above the level of the molars, though the alveolar portion of the 

 maxillary is extremely low. The infraorbital foramen has not quite so anterior 

 a position as in Agriocliccrus, opening above the line between p- a and p A , while 

 in the White River genus it lies above the middle of p 3 . The little that is 

 known of the skull adds no especial probability to the view that this Uinta 

 genus is the forerunner of the White River Agriochcerus, but, on the other 

 hand, it does not in any way render that view less likely. 



Aside from the hind-foot, the only limb-bone preserved in connection with 

 the specimen is the patella. This bone is quite different from that of Pro- 

 toreodon and very like the patella of Agriochcerus, though it is somewhat less 

 thickened in the antero-posterior diameter and less rugose upon the dorsal 

 face, differences which are connected with the smaller size of the animal. The 

 bone is of an elongate, almond-like, shape, broad proximally and tapering to 

 a blunt point distally. The dorsal surface is regularly and smoothly convex 

 in both directions, while the surface for the femoral trochlea is obscurely 

 divided into two facets by a low and broad median ridge. The shape of this 

 ridge indicates that the rotular trochlea of the femur was wider and shallower 

 than in Agriochceriis. This patella is broader and thinner than that of Pro- 

 toreodon, and has a less elevated median ridge upon the femoral surface. 



MEASUREMENTS. 

 Patella, length .... 0.025 ! Patella, maximum width . . 0.017 



Of the pes (Plate IV., fig. 28) are preserved portions of the astragalus 

 and calcaneum, the cuboid and navicular, and the second phalanx of one of 

 the median digits. Of the astragalus we have the proximal half, which differs 

 in some quite marked respects from that of Protorcodon. In the proportions of 

 proximo-distal length to transverse breadth the astragalus is not very different 

 in the two genera, and thus Protagriocliccrus has not yet attained the broad, 

 short, almost hippopotamus-like astragalus of its White River successor. The 

 proximal trochlea is even more asymmetrical than in Protorcodon, the outer 

 condyle much exceeding the inner one in size, though not rising so far above 

 it proximally as in the last-named genus ; the intercondylar groove is broader 

 and more widely open than in the latter, more so even than in Agriochozrus. 



