THE OSTEOLOGY OF ELOTHERIUM. 305 
all, it must have been in a very reduced and rudimentary condition, haying lost all 
functional importance. 
The trapezoid is high, narrow and thin ; it is closely interlocked with the magnum, 
lying in a depression on the radial side of that bone. The facet for the scaphoid is 
simple and strongly convex. ‘Three facets for the magnum occur on the ulnar side, one 
proximal and two distal; the former is much the largest of the three, but is confined to 
the dorsal part of the ulnar side. Of the two distal facets, one is dorsal and one palmar ; 
they are separated by a narrow space and are situated in different planes, almost at right 
angles to each other. On the radial side, near the distal end, is a shallow depression, 
which may haye lodged a rudimentary trapezium, though there is no facet for such a bone. 
The distal side of the trapezoid bears a small, plane facet, of triangular shape, for the 
rudimentary second metacarpal. 
The trapezoid is not yet known in connection with the European species of /lothe- 
rium, or with Anthracotherium. In Hippopotamus it is lower and broader and of more 
functional importance than in Elotherium, as it also is in Sus, and in the latter, differing 
from all of the other genera mentioned, it articulates extensively with the third meta- 
carpal. 
The magnum is a relatively large and massive bone, the three diameters of which are 
nearly equal, though the dorso-palmar dimension somewhat exceeds the other two. The 
dorsal moiety of the bone is the lower, quite a prominent head rising proximally from 
the palmar portion. The palmar hook is represented by a short, but broad, rough and 
massive ridge. The proximal end is unequally divided between the facets for the 
seaphoid and lunar ; dorsally the former is much the wider and occupies almost the entire 
breadth of the bone, but it does not extend so far posteriorly and on the head is con- 
fined to the antero-internal aspect of that elevation. The lunar facet is very narrow on 
the dorsal side, and lateral rather than proximal in position, but posteriorly it widens and 
coyers nearly the entire head. When yiewed from the ulnar side, the lunar facet 
appears to be of a horseshoe-shape, narrow arms extending far down upon the dorsal 
and palmar borders, and separated below by a very large sulcus. These two arms of 
the lunar facet are obscurely demarcated from the two small facets for the unciform, in 
which they may be said to terminate distally. The distal end of the magnum is covered 
by the large, saddle-shaped surface for the third metacarpal, which is convex transversely 
and concave antero-posteriorly ; and proximal to this, on the radial side, is a small facet 
for the second metacarpal. On the radial side also is a depression, running almost the 
full vertical height of the magnum, for the reception of the trapezoid. The depression 
contains a larger proximal and two smaller distal facets for the trapezoid, corresponding 
to those already described on the latter. 
