No. 2.] THE RELATIONS OF PROTOCERAS. 337 



reduced as compared with that of the oreodonts, suillines, etc., 

 but much less so than in the existing Pecora, or even than in 

 Leptomeryx and the tragulines ; in its proximal portion, it is 

 convex on the inner, concave on the outer side ; distally this 

 arrangement is reversed. The shaft tapers inferiorly, but 

 shows a considerable expansion in the antero-posterior direc- 

 tion about three-fourths of an inch from the distal end, from 

 which it rapidly tapers again. The distal end is relatively 

 much larger than in the recent ruminants and is occupied by a 

 saddle-shaped facet for the cuneiform. 



The radius has much the same proportions as in MoschttSy 

 but is somewhat longer. The head is transversely expanded, 

 particularly toward the ulnar side, and antero-posteriorly com- 

 pressed ; it occupies the entire distal surface of the humerus, 

 the ulna having but a minute facet for this portion of the 

 latter. The proximal surface is divided into three nearly equal 

 facets for the corresponding divisions of the humeral trochlea. 

 The shape of the intercondylar pit of the radius in Protoceras 

 is, so far as it goes, a point of resemblance to the oreodonts, 

 but the other humeral facets and the whole shape of the head 

 are entirely different. As these characters are retained with 

 remarkable persistency throughout the whole history of the 

 oreodonts and even in Agriochoerns, the difference is not un- 

 important. 



The shaft of the radius is of nearly uniform size throughout, 

 and is strongly arched forward ; it is rather slender, but yet of 

 the typical modern ruminant shape, i.e., of transversely oval 

 section, and contrasts strongly with the subcylindrical and 

 remarkably slender radial shaft of Oreodon. The distal end is 

 moderately expanded and thickened and bears two roughened, 

 elevated ridges which enclose a sulcus for the extensor ten- 

 dons. The distal facets for the carpus seem to show some 

 variations which may be more or less due to age. Of the 

 young specimen described by Osborn and Wortman these 

 writers say : " The process of bone which bears this facet (i.e., 

 for the scaphoid) is not produced backward, as it is in Tragu- 

 liis, nor has it the marked obliquity seen in Leptomeryx and 

 Cariacus and, to a less degree, in Tragidiis. The scaphoid 



