HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 367 
pus the lateral faces of the tuber were more vertical, or nearly rectangular with 
reference to the sustentacular facet. The lesser process of the distal end is some- 
what less developed than in the majority of the specimens representing Moropus, 
but the sustentaculum is otherwise quite similar, and the facet for the tibia at the 
upper angle of the facet for the astragalus is even more prominent than in any 
of the American forms known to us. The facets for the cuboid in the two genera 
here compared are not unlike. 
The caleaneum of Macrotherium is quite different from that in the American 
genus. In the first place the tuber is more ovate in cross-section and oblique in 
position; secondly, the lesser process of the distal end is larger corresponding to 
the much lower and broader tarsus in Macrotherium. The facet for the cuboid 
also extends farther in the tibial direction, and the tibia, when flexed backward, 
did not touch the caleaneum in the latter form. 
MEASUREMENTS OF CALCANEUM.”? 
No. 2193 Y.M. No. 1706a No. 1701 No. 1424 
(M. elatus, type), (M. elatus), (M. petersoni), (M. hollandt), 
mm, mm. mm. mm. 
Greatest length including the tuber............... 155 155 117 107 
Wmenothyoistwbersceerer yam arcane cae ale cicnasine 90 90 77 65 
Length of sustentacular facet.................... 67 67 50 45 
Transverse diameter at sustentacular facet......... 98 93 68 73 
Navicular (Fig. 100).—The navicular is broad, quite deep, and thin. Its 
dimensions are more nearly like those of the same bone in EKquus, than in other 
Perissodactyla. In detail, however, the bone differs from that of the horse in 
having a less developed palmar proc- 
ess and by the fact that the articu- 
lation for the cuboid is more ex- 
tensive. The articulation for the 
astragalus is quite plane with the 
exception of the sudden upward cur- 
vature on the plantar tibial angle 
which is identical with the condi- Fie. 100. Nawvicular of right foot of M. She (No. 
tion in Equus. On the fibular face 1706A). X43. 1, anterior view; 2, fibular view, showing 
there is sometimes a small facet facet for cuboid; 3, posterior view; 4, tibial view, face for 
which articulates with a correspond- 
ing facet on the tibial face of the 
cuboid. The main facet for the cuboid is long antero-posteriorly and narrow 
mesocuneiform; 5, inferior view, surfaces for cuboid and 
cuneiforms; 6, superior view, face for astragalus. 
7 Italicized numbers estimated. 
