520 
THE OSTEOLOGY OF HY^NODON. 
un- 
the 
<1„ !,. Mestnyx, Oxy^na, Cmis, Hyxm, etc., and tlie trochlea of the latter is 
equally divided by the oarina, ivbicli is slightly nearer to the radial than to 
Tlie liftli metacarpal is very short, only slightly exceeding the first m lengtli, 
to which it bears a close resemblance in shape and appearance. The proximal end 
is considerably expanded, and carries on the ulnar side a prominent rugosity tor 
ligamentous attachments. The facet for the unciform is narrow transversely, but 
much extended antero-posteriorly, and very strongly convex ; it articulates only 
with the distal side of the unciform and does not extend up upon the ulnar side. 
The facet for me. IV is of crescentic shape, the dorsal horn being convex and pro- 
jecting, while the palmar horn is flat. The shaft is stouter than that of me. I, more 
arched and more strongly compressed antero-posteriorly, while the distal trochlea 
is much broader, especially on the palmar side. 
The metacarpus of Oxycena is decidedly different from that of Hytenodon. The 
bones are even shorter, weaker and more slender in proportion to the size of the 
skull. The digits are disposed more symmetrically. III and IV forming one pair of 
nearly equal length and weight and, apparently, II and V another pair. In Hyce- 
nodem^ on the other hand, the metacarpals are all of different lengths, the order being 
III, IV, II, V, I, and they are arranged so as to diverge from one another more than 
in Oxycena, though much less than in Patriofelis. The carpal connections are also 
dillerent in the two genera, hi Oxycena me. II has an extensive articulation 
with the trapezium, but does not reach the magnum, while in the White River 
genus the magnum process is very prominent and the facet large. The unciform 
process of me. Ill is in Oxycena rather small, but decidedly larger than in Hyce- 
nodou, while the head of me. V has a concave facet for the unciform, and embraces 
both the distal and external sides of that bone. The only^ other creodoiits, the 
structure of whose manus is completely known, axQ Mesonyx ?cnd Palriofelis ; in the 
former the manus is of an entirely different type, approximating more to the condi- 
tion assumed by the hyrnnas, while the latter is not notably diflerent from Oxycena. 
The phalanges of the various digits in Hyeenodon differ from one another only 
m size and in the degree of curvature which they display. The proximal phalanx 
IS of only moderate length, but broad, heavy and depressed. The proximal end is 
broad and thick, with a shallow articular surface for the metacarpal, which is deeply 
notched at the palmar border; a notch which would seem to be wider and deeper 
than necessary for the metacarpal carina which it accommodates. The shaft is 
briwul, stout ami strongly arolied toward the dorsal side. The distal trochlea is of 
rather small dorso-palmar diameter and but imperfeetl, divided into two facets by a 
h!d ir ‘ '>»“ >i°t encroach ufmii the dorsal face of tlie bone, 
t i, „l I "'a 0 There is some resemblance between 
n ore sle r d “L“”yP“"<‘“S Caniy but the latter is more elongate, 
deeply dTptLt. .^Lddlt “ “ 
The second phalanx is short and depressed, but very broad. The pmximal 
