342 MEMOIRS OF THE CARNEGIE MUSEUM. 
face is taken up by the articular facets for the pisiform and the ulna. The facet . 
for the ulna is gently convex transversely, concave antero-posteriorly; it occupies 
nearly two-thirds of the proximal face, and its general outline is a long oval. The 
facet for the pisiform occupies more than one-third of the proximal face; it has an 
elevated position on the postero-ulnar portion of the bone, and is separated from 
the facet for the ulna by a gently rounded ridge in a manner which gives the articular 
surface a wedge-shaped outline, with the postero-ulnar portion of the facet the 
broadest, and the apex directed dorso-radially. The radial face has, distally, 
a large plane facet for the lunar, crescent-shaped in outline, while proximally 
there is sometimes a minute facet on the overhanging proximal border, touching a 
corresponding small facet on the ulnar face of the lunar already described. Between 
these two facets the face of the bone appears to be excavated, due in a great measure 
to the overhanging superior border mentioned above, and which is also plainly 
indicated in the illustration, Fig. 82, 1, 4. 
The posterior portion of the cuneiform of Nestoritherium, as represented by 
the cast, is broken off, but what remains indicates similarity to that of Moropus. 
The cast as a whole reveals a bone having relatively a smaller vertical diameter 
than in Moropus, the dorso-radial angle less sharply developed, and the articular 
facet for the unciform more sharply concave antero-posteriorly than in the American 
genus. 
In Macrotherium the posterior part of the cuneiform is also broken off, but from 
the anterior portion it is very evident that the bone is quite different in its general 
outlines and also in minuter details. Thus the dorso-radial angle is very high pro- 
portionally and very rapidly decreases in height in the ulnar direction, due to the 
extremely oblique or almost lateral articular facet for the ulna. The transverse 
line of contact between the carpus and the ulna-radius is thus unusually convex 
transversely, especially on the ulnar side. In Moropus elatus and Nestoritherium 
the proximal articulations of the cuneiform are even somewhat less oblique than 
in Titanotherium, the facets for the ulna and pisiform of the American genus 
being not unlike those in the Titanotheres. The cuneiform of Titanotherium is, 
however, relatively smaller and the superior and inferior facets for the lunar are of 
more nearly equal size than in Moropus elatus. 
MEASUREMENTS OF CUNEIFORM. 
No. 1604 No. 1700 
(M. elatus), (M. petersoni), 
mm. mm. 
Greatestitransverseralametersenae eee ei eee eee 46 30 
Greatest antero-posterior diameter.......................-. 69 49 
Greatestiverticalidiameter. si)... ohe cis See oo eee 43 30 
