HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 300 
by a prominent ridge, which extends across the entire antero-posterior surface 
between the articulations. On the radial side of this ridge quite proximally, and 
near the dorsal face is located one of the articular facets for Me. III. The other 
facet is more lateral and nearer the palmar angle. On the ulnar side of the ridge 
mentioned is a large facet for the unciform, which is suboval in outline, slightly 
concave transversely and unevenly convex and concave antero-posteriorly. Below 
the head on the radial and palmar faces the shaft presents a rough surface which 
is sometimes developed into ridges paralleling the shaft, and serving for muscular 
attachments. On the ulnar palmar angle is a massive tubercle, which is bisected 
by a deep and broad excavation, the posterior portion being the palmar tubercle 
shown in Fig. 90, 2. The anterior portion of this tubercle is well illustrated in the 
articulated manus (Pl. LX VIII,1,2). Atthe base of these overhanging tubercles 
is a facet for Me. V, which in.some individuals is bisected by the downward con- 
tinuation of the broad excavation described above. 
The facet is in an oblique position to the long axis of . aN \ o> . 
the shaft and is concave antero-posteriorly as well as \\" ny ON A) 
supero-inferiorly, plainly showing that Me. V did not Ce 
articulate with the unciform, as has already been 
pointed out by Peterson." The distal end is very 
like that of Me. III except that the larger of the two 
protuberances, on the dorsal face, is on the radial in- 
stead of on the ulnar angle, asin Mc. III (see Fig. 90, 2). 
The head and the upper end of the shaft of Me. IV 
in Nestoritherium pentelici present a number of 
points of difference when compared with Moropus 
elatus. For instance the articular facet for the unci- 
form is larger and more basin-shaped, the facet for 
Me. III is not divided into two portions, and there is 
a total absence of a facet for Me. V. Externally the 
shaft of Nestoritherium is deeply furrowed by rugosi- 
ties and the shaft itself is trihedral in cross-section with a backward bow while that 
of Moropus is more nearly cylindrical and straight. 
In Macrotherium grande Me. IV, though bearing a general resemblance to 
that of Moropus elatus and Nestoritherium, is quite unlike it in detail. In the first 
place this element in the remains from Sansan is the longest in the series; secondly, 
the palmar radial angle of the lower portions of the shaft and distal end is relatively 
& Am, Naturalist, Vol. XLI, p. 747, 1907. 
of M. elatus (No. 1604). xX. 1, 
lateral view; 2, dorsal view. 
