HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDBA. 339 
palmar process is more prominent, and the articulating facet for the trapezoid 
is decidedly basin-shaped, while in Macrotherium and Moropus it is more saddle- 
shaped, due chiefly to the descending process on the dorso-ulnar angle described 
above. The principal articulation for the magnum is therefore confined to the 
posterior portion of the scaphoid, while in Macrotherium and Moropus they are 
located more dorsally. There is no facet for the trapezium, the radial angle of 
the scaphoid having no such development as in Moropus. 
While the secaphoid of Macrotherium is higher than in Nestoritherium and has 
the heavy descending radial arm as in Moropus, it differs from the same element 
in the latter genus in almost every detail. The articulating surface for the radius 
of Macrotherium covers the entire superior face and is concave antero-posteriorly, 
while in Moropus the surface is plane and does not extend to the posterior face. 
The latter face of the scaphoid in Moropus as well as in Nestoritherium has a rugose 
palmar tubercle, which extends directly backward and is provided with no portion 
of the articular facet for the radius, while in Macrotherium, the palmar tubercle 
is directed more upward and backward with the facet for the radius well back 
towards the extreme posterior face. The articulating face for the lunar is con- 
fined almost entirely to the ulnar face of the distal beak-like process, the proximal 
portion of the bone having rather poorly defined facets for the lunar. The beak- 
like process appears less cube-like than in the American form and is more wedge- 
shaped with the apex directed backward. This process however extends down- 
ward and outward and comes in contact with the magnum in a similar manner 
as in Moropus elatus. Distally the scaphoid is taken up almost entirely by the 
large and obliquely concave facet for the trapezoid. There is apparently no 
facet for the trapezium. Altogether the scaphoid in Macrotherium and Nestori- 
thervum is unlike that in the Titanotheres, while in Moropus elatus this bone is 
more similar to that of the Titanotheres. 
MEASUREMENTS OF SCAPHOID. 
No. 1604 No. 1700 No. 1424 
(M. elatus), (M. petersoni), (M. hollandi), 
mm. mm. mm. 
Greatest transverse diameter............-.---eeceece cess eceeee 54 38 40 
Greatest antero-posterior diameter...................e-eeeeeeee 62 44 52 
Greatesumenuicaludiameteceepases ae ena ene a aera 54. 34 40 
The Lunar (Fig. 80).—The lunar has a smaller transverse, but greater antero- 
posterior and vertical, diameter than the scaphoid. The articulating face for the 
radius is very convex antero-posteriorly and very gently convex laterally. This 
facet does not extend in the palmar direction as in Titanotherium, the palmar proc- 
