Marsh Collection ,. Peabody Museum. 



381 



47 



which are very concave from side to side, and convex from 

 before backward. In its transverse concavity, the capitnlum 

 differs from that of the dog, in which it is nearly flat. The 

 humerus and scapula are of nearly equal length. 



The ulna, figure 47, differs from that of the dog in being 

 shorter, heavier, and stouter in every way. The olecranon is 

 of great proportional length, and in 

 this respect, like so many other 

 Creodonts, betrays its marsupial re- 

 lationship. The proximal end is 

 traversed by a vertical groove, the 

 inner or radial lip of which is un- 

 usually prominent. The sigmoid 

 cavity is deep ; its posterior wall is 

 hook-shaped, and considerably over- 

 hangs the articular surface. The 

 shaft is somewhat flattened from 

 side to side and is traversed by a 

 deep longitudinal groove. The sty- 

 loid process is rather short and 

 obtuse. 



The radius, figure 47, is about 

 equal to that of the dog in size, 

 although somewhat shorter; it is 

 not quite as long as the humerus, 

 and is a little longer than the fore 

 foot. The proximal articular sur- 

 face is flattened from before back- 

 ward, and the proximal extremity 

 articulates with the entire distal end 

 of the humerus. This surface may 

 be described as having a central 

 concavity, with a rounded sloping 

 edge internally, and an anteriorly 

 beveled articular face, occupying 

 the antero-external angle. The ar- 

 ticular surface for the ulna is much 

 flattened as in the dog, and is con- 

 fined entirely to the under side, so 

 that the power of pronation and 

 supination was not greater than in 

 the living Canidse. The tubercle 

 for the insertion of the biceps is 

 placed upon the outside, just below 

 the proximal extremity, as in the 



(\cxr ATifl is small TVip elm ft ih nval The radius is represented as 



aog, ana is small, ine snait is oval slipped down below its natural 

 m transverse section, slightly curved, position. 

 and has a well-marked ridge upon its 



Figure 47. — Right ulna and 

 radius of Dromocyon vorax 

 Marsh; front view; one-half 

 natural size. (Type.) 



