PETERSON: A REVISION OF THE ENTELODONTIDZ 123 
Scott described (/. ¢., p. 307). They are small nodular bones with well defined facets 
for Me. III, the magnum, and the trapezoid, but with no facet for the trapezium. 
Metacarpal III. — Unfortunately the third metacarpal is represented only by 
the proximal and distal ends, as the contact of the shaft was lost in collecting the 
material. The head is much expanded transversely, especially on the ulnar side, 
which has a heavy cubital process articulating with Me. IV and the unciform in an 
interlocking manner. Besides the dorsal articulation for Mc. LV, there is also a 
palmar articulation on the ulnar side, which is located on the very prominent palmar 
process. Continuous with the latter facet, and separated from it only by a sharply 
defined ridge, is a facet evidently for a palmar sesamoid.” Proximally the bone is 
taken up by the large facet for the magnum, which is convex antero-posteriorly and 
concave laterally. On the dorso-ulnar angle is a smaller and obliquely placed facet 
for the unciform referred to above. The radial side is excavated quite deeply and has 
two facets, one dorsal and one palmar, for the rudimentary Me. IT; the dorsal facet 
is quite large and is wedge-shaped in outline with the apex downward ; the palmar 
facet consists only of a minute rounded ridge on the radial angle of the articular 
surface of the magnum. ‘The shaft of the bone is quite broad transversely and com- 
pressed antero-posteriorly. When held in a vertical position the distal trochlea is 
well shown on the anterior face of the bone, less so behind. The metapodial keel 
is confined only to the plantar portion and is proportionately less developed than in 
the Oligocene genus. In general appearance there are no very marked differences 
of the metacarpals from those of the known earlier forms; though in the present 
genus they are relatively of slightly greater length, and have rugosities on the inner 
sides. The comparative length of the metapodials with the upper arm-bones is a 
significant feature in Dinohyus. 
Professor Scott states that the third metacarpal in Kowalevsky’s specimen (87, 
p- 807) “does not differ in any important way from that of the American species, 
though the magnum facet is somewhat more concave transversely and the shaft is 
rather more slender.” Kowalevsky, however, points out (38, p. 444, Pl. XX VI, fig. 23) 
that there are three facets on the radial face of Me. III, of which the two lower undoubt- 
edly articulated with the rudimentary Mc. I, while the upper one articulated with 
the trapezoid. In all the specimens of the -American forms, which | have examined 
and in which these parts were present, I have not been able to find more than two 
facets, those for Me. II, on the radial face of Me. III. From this fact it is quite evi- 
dent that the trapezoid in Hntelodon had not suffered the reduction, which is seen 
51 Tn specimen No. 2136 (Carn. Mus. Cat. Vert. Foss.) this palmar process was found very nearly in position (see 
fig. 70, ps. ). 
