HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 357 
from the facet on the ulnar face of Me. IV in the cast of the original specimen, 
and also from the description and illustrations given by Filhol. 
Sesamoids.—The sesamoids are of large size and vary in shape and robustness 
according to their position. The facets for the metapodial grooves are generally 
concave antero-posteriorly, irregularly convex transversely and oblong in outline. 
The two sesamoids on one digit often touch each other by decided facets and occasion- 
ally they are found to be solidly coéssified as is sometimes the case in the Titanothe- 
rude. ‘They are much lighter proximally than distally, and the lateral borders of the 
plantar face show a rough ridge so that when the two sesamoids are placed in position 
there is developed between them a broad groove for the tendons. The positions 
which the sesamoids most probably had are best seen in the palmar view presented 
on Plate LXIX, Fig. 2. There were no sesamoids found located in their proper 
positions and the arrangement here presented must be regarded as partly con- 
jectural pending the discovery of these parts in position, but the contacts furnished 
by the specimens employed are so perfect as to leave little doubt as to the correct- 
ness of the restoration given in the plate. 
There are no sesamoids present in the casts of the manus of Macrotherium or 
Schizotherium priscum here used for comparison. 
MEASUREMENTS OF FirtH METACARPAL. 
No. 2462 No. 1700 
(M. elatus), (M. petersoni), 
mm. mm. 
Greatestilen ohne seman: eye enn Riel te cnvnnep ung Lt 140 105 
Greatest transverse diameter of head....................-.. 24 25 
Greatest antero-posterior diameter of head................... 27 18 
Greatest antero-posterior diameter of distal end.............. 24 16 
Greatest transverse diameter of distal end..............-.--- 25 21 
The Phalanges. 
The first and second codéssified phalanges of the second digit in the manus 
of Moropus elatus are highly characteristic. The bone was described by Pro- 
fessor Marsh as early as 1877, and again identified as the phalanges of the 
second digit, described, and illustrated by Mr. Peterson in 1907. The proximal 
articulation of this duplex bone is nearly circular in outline and decidedly cup- 
shaped, with the ulnar border the sharper and more prominently developed. A 
surprising feature, showing a remarkable ability to flex the first joint of the digit, 
is revealed by the fact that directly anteriorly and also radially there are some- 
62 Am. Jour. Sci., Vol. XIV, pp. 249-251, 1877. 
6 Am. Naturalist, Vol. XLI, pp. 747, 1907 (illustrated, p. 735, Figs. 9, 17; p. 746, A). 
