122, MEMOIRS OF THE CARNEGIE MUSEUM 
of Hippopotamus, though somewhat less produced downwards. At the base of this 
palmar process on the ulnar side there is a facet for Mc. V, which meets the facet 
for the pyramidal at right angles. In Archxotheriwm ingens these two facets are 
separated by a considerable surface, which is concave vertically and convex trans- 
versely. The radial side is occupied by a large facet for Me. III, which is strongly 
inclined radially. Back of this facet is a large excavated area, which extends over 
the remainder of the radial face of the bone. The small oblique facet for the mag- 
num on the radial angle of the unciform in Archxotheriwm is almost entirely proximal 
in Dinohyus, and passes imperceptibly into the lunar facet. Proximally the lunar 
and pyramidal articulations are divided by a prominent ridge, which extends antero- 
posteriorly, the pyramidal facet being the larger of the two. The distal face is occu- 
pied almost entirely by the large facet for the fourth metacarpal, which on the 
radial angle presents an abrupt continuation of the facet for Me. IIT asin Archeo- 
theriwm. There is no dorsal articular surface for the magnum on the radial face, as 
in older forms” of this family, and these two bones (unciform and magnum) when in 
position in the carpus appear well separated (see fig. 70). 
Professor Scott has already pointed out that “the unciform of Kowaleysky’s 
specimen does not differ in any significant way from that of the American species” 
(87, p. 306). In Hippopotamus and Sus the unciform is larger, which is due to the 
tetradactylous condition of the feet in these genera. 
MEASUREMENTS. 
Mm. 
Unciform, greatest antero-posterior diameter. 64 
“ ‘transverse & 54 
He fe vertical ct 47 
Metacarpal I. —'The second metacarpal is not present in the type of Dinohyus, 
but a deep vertical groove on the lateral face and a minute articular facet on the 
proximal angle of the third metacarpal indicate the presence of this bone. In 
my notes on Bodchwerus humerosus in the American Museum, I find it stated that 
Metacarpal II has two facets proximally: one small one for the trapezoid and a 
larger one for the facet on the radial face of Mc. III. The reduction of these two 
elements (trapezoid and Mc. II) in the manus of the Nebraskan Miocene form is in 
all probability carried to a greater degree than in the John Day form. The second 
metacarpals of the fore feet are present in the Princeton specimen, which Professor 
In the type of Bodcherus humerosus the unciform and magnum are separated, but not to the same extent as in 
Dinohyus; the beak of the lunar in the latter genus extends lower down than in the former. This fact is not well illus- 
trated in fig. 15 on page 61 where the lunar appears too low. 
