344 SCOTT. [Vol. XL 



throughout, thickening somewhat toward the distal end ; in 

 section it is an irregular quadrate, with nearly equal transverse 

 and dorso-palmar diameters, but the palmar surface is much 

 narrower than the dorsal. The ulnar side of the shaft of 

 mc. Ill and the radial side of mc. IV are flattened, so that 

 the two bones are closely approximated. The distal trochlea 

 is very different from that of Oreodon and resembles the 

 pattern found in Ge locus and Pcebrothet'hiin. In Oreodon this 

 structure is low and wide, very strongly convex, and separated 

 from the dorsal surface of the shaft by a deep, narrow pit ; 

 while in Protoceras, as in the other genera mentioned, it is 

 higher and narrower, the convexity is not so marked, and the 

 articular surface is separated from the face of the shaft only 

 by an almost imperceptible ridge. As in all the genera named, 

 the carina is confined to the palmar side. The radial side of 

 the shaft is flattened for about two-thirds of its length by the 

 contact of mc. II. 



Compared with the third metacarpal of Gelocits that of Pro- 

 toceras is straighter, with less broadened and thickened head, 

 it has an excavation on its radial side for the head of mc. II. and 

 a larger unciform process ; otherwise the two are much alike. 



The fourth metacarpal is the counterpart of the third, except 

 that it is shorter and rather more slender proximally, while the 

 distal portion of the shaft is somewhat broader and more com- 

 pressed antero-posteriorly. The head is no broader than the 

 shaft, but has a greater fore-and-aft diameter, owing to the 

 presence of a palmar projection. The unciform facet is 

 slightly concave transversely. Both of the median metacar- 

 pals are proportionately short ; while the scapula and the fore- 

 arm bones are considerably longer than in MoscJms, the median 

 metacarpals are noticeably shorter, and even in the musk-deer 

 the anterior cannon-bone is by no means elongate. The relative 

 length of the metacarpals in Protoceras is more nearly that seen 

 in Dorcathermm. 



Metacarpal V is shorter and distinctly more slender than 

 mc. II, but otherwise shaped like it; the head has a rugosity 

 on the ulnar side for ligamentous attachment. The unciform 

 facet is small, of triangular shape and, but for a small con- 



