62 SCOTT. [Vol. V. 



intercondylar ridge is narrow and sharp. The articular surface 

 is high both in front and behind ; the anconeal fossa is deep and 

 appears to penetrate the shaft. 



The ulna and radius are closely applied together, but do not 

 coalesce, except partially at one point in the proximal portion, 

 whatever may be true of the distal. The former has a heavy 

 and prominent olecranon, which, so far as it is preserved, is con- 

 tinued upward in the line of the shaft, and does not project 

 backward at all ; the sigmoid notch is deeply incised with a 

 decurved proximal margin ; both internal and external humeral 

 facets are continued down the anterior face of the notch. At 

 the level of the head of the radius the shaft is quite broad and 

 thick, but rapidly tapers below this point. The head of the 

 radius is narrow, and the groove for the intercondylar ridge is 

 very shallow and does not notch the front margin. The shaft, 

 so far as preserved, is much more slender and rounded than in 

 Pcebrotherittm. 



In Pcebrotherium, the shape of the scapula agrees best with 

 that of the llama, as do also the position of the spine, shape 

 of the acromion, and relative size of the pre- and post-scapular 

 fossae, but the coracoid, though much larger than in Lepto- 

 tragulus, is much smaller and less rugose than in the llama. 

 The neck and coraco-scapular notch are more like those of the 

 camel. 



The humerus is very different from those of the later genera ; 

 the distal end is like that of Leptotragulus, but the intercondylar 

 ridge is broader and more rounded, though less so than in the 

 existing genera. The shaft is much more slender than in the 

 latter, the proximal end remarkably different ; the external 

 tuberosity is very high and broad, extending across the whole 

 anterior face of the bone and overhanging the bicipital groove. 

 This groove is narrow, deep, and placed at the antero-internal 

 angle of the head, and the very small rudiment of a bicipital 

 tubercle may be seen at the bottom of it. The internal tuber- 

 osity is very small. 



The ulna and radius are firmly co-ossified throughout, but are 

 separated at two points by the proximal and distal interosseous 

 foramina. The shaft of the radius is much broader and flatter 

 than in Leptotragulus, though much more slender than in the 

 recent species. The head is also narrower than in the latter ; 



