118 DINOCEKATA. 



The i^roximal face (Plate XXXIV, figure 11) is obliquely saddle- 

 shaped, and presents two confluent, but distinguishable, faces, one for the 

 lunar, and one much larger, for the pyramidal. 



The face for the lunar lies along the inner, or radial, side of the 

 proximal surface, and is sigmoid from before backwards, and transversely 

 more or less convex. Its posterior half is considerably elevated above 

 tlie anterior, to fit into a corresponding excavation in the lunar. 



The face for articulation with the pyramidal is somewhat in the form 

 of a quadrant, one side being confluent with the face for the lunar, the 

 other side running along the outer, or j)osterior, margin of the bone, while 

 the curve forms the upper limit of the dermal surface. This face is 

 strongly saddle-shaped, concave anterq-posteriorly, and convex from side 

 to side. 



The distal surface of the unciform (figure 12) bears three concave 

 articular faces for the support of the third, fourth, and fifth metacarpals. 

 Of these, the inner is the smallest, triangular in outline, only slightly 

 concave, and aids the magnum in the support of tlie middle, or third, 

 metacarpal. 



The second, or median, articular face is tlie largest, and is more 

 deeply concave than the first. It extends antero-posteriorly quite across 

 tlie distal end of the bone, but is much broader in front than behind. 

 It supports the fourth metacarpal. 



Tlie third articular face, situated upon the outer, or ulnar, side of 

 tlie distal end of the unciform, is more strongly concave antero-posteriorly 

 than either of the others, and is nearly as broad behind, or on its jialmar 

 margin, as in front. It is oblique to the axis of the bone, and, as already 

 mentioned, may even be confluent for a short distance with the proximal 

 face for the pyramidal, as shown in figure 123, below. 



The unciform bone in two individuals of the Dinocerata is represented 

 in the woodcuts below. The specimens figured show marked difi'erences, 

 but whether these are constant in all the species of the t^^•o genera cannot 

 at present be determined. Tins is the ease, also, with other carpal bones. 



