HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 347 
and articulates with the unciform. In front and back of this articulation the 
ulnar face of the bone is excavated in a manner similar to that on the radial face 
(Fig. 86, 3). There is a palmar hook of considerable size which extends well down 
and helps to support the palmar portion of the large articular surface for Me. III. 
On the superior face the anterior portion of the facet for the lunar lies on the ulnar 
side of a sharp crest (Fig. 86, 5), while farther back the surface rises and broadens, so 
that the posterior portion of the lunar 
takes up the entire postero-proximal 
face of the bone. The articulation for 
the scaphoid lies on the radial side of 
this crest and is described above. 
Distally there is one large and irregu- 
larly shaped facet for Mc. III. This 
facet is divided into two portions by 
a lateral constriction, and sometimes Fic. 86. Magnum of left manus of M. elatus (No. 
1604). Xz. 1, dorsal, 2, radial, 3, ulnar, 4, posterior, 
5, proximal, 6, distal, views. 
also by a faintly developed ridge 
which extends nearly directly antero- 
posteriorly. The portion on the radial side of the ridge is the smaller and is 
much concave antero-posteriorly, while the larger portion of the ulnar side rises 
upward and outward in an oblique manner in the anterior region and descends 
posteriorly, forming a broad beak-like process of the palmar termination. The 
magnum is thus wedged in between Me. II and III in such a manner as to impart 
almost complete rigidity to the bone, while its proximal surface shows more indi- 
cation of flexure between magnum and lunar. 
In Nestoritherium the general outline of the magnum is strikingly similar to 
that in Moropus. There are differences in detail, however, of which the most 
noticeable is the absence of the large square facet (for the descending arm of the 
scaphoid (see Fig. 79, 1 and 4, p. 338)) on the proximal face at the dorso-radial 
angle, which is present in the American genus. The curvature of the facet for 
the lunar is also gentler in Nestoritherium than in Moropus. 
The cast of the magnum of Macrotheriwm from Sansan employed for com- 
parison indicates that this bone is incomplete, especially in the distal palmar 
region. ‘The anterior portion, which appears to be more complete, presents a 
general similarity to the same bone in Moropus elatus, except for the absence of the 
large truncated tubercle on the dorsal face, which is so conspicuous in Moropus 
and Nestoritherium. ‘The facet for the scaphoid in Macrotherium is more distinctly 
54 In No. 1604 there is evidence of this ridge. 
