32 SCOTT. [Vol. V. 



In correspondence with the narrowness of the humeral troch- 

 lea, the head of the radius is but slightly broader than the shaft. 

 The articular surface is divided into two concave facets by a 

 very low ridge which forms an inconspicuous projection on the 

 anterior margin. As the external facet is much larger than 

 the internal, this projection is internal to the median line of the 

 head, but placed nearly in that of the shaft, for the expansion 

 of the head is principally towards the outer side. The shaft of 

 the radius is very slender and of transversely oval section, with 

 the inner border somewhat sharper than the outer : it gradually 

 thickens below the middle of its length, as well as becoming 

 broader. The bicipital tuberosity is very small and inconspic- 

 uous, and is placed some distance below the head, on the inter- 

 nal border. The distal end is much thicker and broader than 

 the proximal, though less expanded than in the modern genera. 

 The anterior face is slightly roughened and exhibits the grooves 

 for the extensor tendons even more distinctly than in the 

 camel. The distal face exhibits three well-separated facets 

 for the proximal row of carpals, which are placed somewhat 

 obliquely to the transverse axis of the radius. The surface 

 for the scaphoid is concave in front, convex behind, and is 

 reflected far up upon the posterior side of the radius, giving 

 the bone greater depth (antero-posteriorly) here than elsewhere. 

 The lunar facet is separated from the scaphoidal by a sharp 

 ridge : it also is concave in front, convex behind, but is not 

 reflected upon the posterior side of the radius, except for a 

 small articular surface which is visible on the ulnar side of the 

 projecting posterior portion of the scaphoidal facet. The cunei- 

 form surface is large, and covers almost the whole of that bone, 

 the ulnar contact with it being very much reduced. The 

 cuneiform surface of the radius is saddle-shaped, concave from 

 side to side, and convex from before backwards, and reflected 

 upon the posterior side of the radius, passes into the surface for 

 the pisiform, which is more on the radius than on the ulna. 

 There is, however, no such projection at this point as is formed 

 by the scaphoidal facet. Large as it is, the cuneiform facet of 

 the radius is relatively smaller than in the modern forms, where 

 it covers the entire proximal surface of the cuneiform when 

 viewed from the front, the ulna being pushed to the postero- 

 external angle. 



