HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 343 
The Pisiform (Fig. 83).—The pisiform of No. 1604 is not present, but this 
element of the carpus is well represented in the abundant material in the Carnegie 
Museum. The pisiform of a fore foot (No. 1442) has been selected for description 
as it has been employed in the mounted skeleton of Moropus elatus. The large 
facet on the cuneiform for the pisiform has been referred to above and the pisiform 
is found to correspond in magnitude, as shown in Fig. 88. The facets for the 
cuneiform and ulna are sub-equal in size and are separated by a sharp ridge; the 
former facet is nearly parallel with the long axis of the bone, while the latter has a 
more oblique position. Immediately back of the facets there is a prominent 
swelling on the internal face, which extends from the inferior border and increases 
in prominence in its upward course, terminating in a large tubercle on the superior 
border of the bone. Back of this enlargement the shaft of the pisiform is con- 
stricted and its free end is again expanded and abruptly rounded. 
The pisiform of Nestoritherium is very similar to that of Moropus elatus, 
but this bone is not represented in the cast of the fore foot of Macrotheriwm in 
the Carnegie Museum. 
MEASUREMENTS OF PISIFORM. 
No. 1442 No. 1700 
(M. elatus), (M. petersoni), 
mm. mm. 
Greatestslemot hmumen var cana aby alee pmdii oak er Unter eh ee 74 46 
Createsiuransverseidiamelernen eee enn aa asa ee 34 24 
33 
Fic. 83. Pisiform of left manusof M. elatus (No. 1442). Fic. 84. Trapezium of M. elatus (No. 
<4. 1, dorsal view; 2, palmar view; 3, articular view; 4, 1604). X4. 1, superior view; 2, inferior 
superior view; 5, inferior view. view; 3, internal view; 4, radial view. 
The Trapezium (Fig. 84).—The trapezium is moderately large, in shape 
asymmetrical and nodular. The ulnar face of the bone is taken up by a large, plane, 
articular surface for the trapezoid and Me. II (see Fig. 84, 3). On the superior 
face of the bone is an articular facet for the scaphoid, irregularly oblong in outline 
(Fig. 84, 1); this facet is slightly concave laterally in order to conform with the 
