308 THE OSTEOLOGY OF ELOTHERIUM. 



Iii E. magnum, Kowalevsky 's figure shows a somewhat differently shaped proximal 

 end ('76, Taf. XXVI, Figs. 21, 24), the head is somewhat more extended transversely, 

 especially toward the ulnar side, while the palmar projection is narrower and less 

 prominent. In Anthracotherium the head of mc. iii has no such transverse extension. 



Metacarpal F'is an almond-shaped nodule, almost exactly like the specimen figured 

 by Kowalevsky (Taf. XXVI, Fig. 25), though of a rather more regular outline. Proxi- 

 mally the nodule has quite a large, subquadrate, and slightly concave facet for the unci- 

 form, which presents more laterally than superiorly, and forming a very obtuse angle with 

 this surface, is a smaller, triangular facet for mc. iv. 



The metacarpus of Hippopotamus has four functional members, though the median 

 pair are longer and stouter than the lateral. Compared with those of Elotherium they 

 are relatively shorter and much heavier. In Sus there are also four metacarpals, but 

 the laterals are much reduced, while the median pair, which carry most of the weight, 

 are very short and thick, and the distal carina surrounds the entire trochlea, dorsal as 

 well as palmar. The mode of articulation between the carpals and metacarpals is 

 quite different from that found in either Elotherium or Hippopotamus, the head of 

 mc. iii being much broadened and articulating extensively with the trapezoid, so that 

 inc. ii is cut oil' from any contact with the magnum. This is what Kowalevsky has 

 called the " adaptive method " of digital reduction, and it is in decided contrast to the 

 inadaptive method exemplified in Elotherium. 



The phalanges, which are quite" short, a- compared with the length of the meta- 

 carpals, are developed only in the median pair of digits. The proximal phalanx of 

 digit iii is relatively elongate, straight, broad and depressed ; its proximal end is both 

 wide and thick, and carries a concave facet for the metacarpal trochlea, which is deeply 

 notched on the palmar border tin- the carina. Toward the distal end the phalanx 

 narrows hut little, though diminishing much in the dorso-palinar diameter; the distal 

 trochlea is low, wide, depressed and only slightly notched in the median line. The 

 second phalanx is short, broad and thick, and of quite asymmetrical shape; its proximal 

 trochlea is obscurely divided into two facets, of which that on the radial side is the 

 larger and extends more in the palmar direction, while the median dorsal beak is not 

 prominently developed. The distal trochlea is much thicker than that of the first 

 phalanx, is reflected much farther upon the dorsal face, and is more distinctly notched 

 in the median line. The course of this surface is oblique, so that it faces somewhat to 

 the ulnar side. The ungual phalanx is curiously small and nodular in shape, and is 

 short, lint quite broad and thick; the proximal trochlea is imperfectly divided into two 

 slightly concave facet-. The palmar surface is nearly plane, except for its rugosities, 

 while the dorsal margin descends abruptly to the blunt distal end. 



