354 
PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 
in Sarcophilus and Prothylacynus. In shape, the scaphoid resembles 
more closely that of Sarcophilus than the corresponding element in 
Thylacynus. 
The lunar is a wedge-shaped bone, the proximal end of which is occu- 
pied by a broad, convex facet for the radius. Distally, the lunar articulates 
by a concave, oval facet with the magnum, unlike Thylacynus (cf text 
fig. 4, a). The scaphoidal facet is semilunar in outline, almost plane in 
dorso-palmar section and plane or slightly convex at right angles to the 
former diameter. The facet for the cuneiform is triangular in outline and 
slightly convex in all diameters. It is feebly differentiated from the semi- 
lunar facet for the unciform. 
The pisiform has a concave, elliptical facet for articulation with the cunei- 
form and a semilunar, dorso-palmarly convex facet for contact with the 
styloid process of the ulna. It is slightly more robust than in Thylacynus , 
terminating distally in a large hemispherical tubercle. 
The trapezium is much larger than in Thylacynus. It is irregularly 
oblong in form, with a B-shapecl facet for the scaphoid, a semilunar facet 
for the trapezoid, convex dorsally and slightly concave toward the palmar 
margin, and a large, concave, oval facet for the metacarpal of the pollex. 
The magnum resembles that of Sarcophilus rather than the correspond- 
ing element in Thylacynus. Proximally, it supports a heavy crest with two 
facets for the scaphoid and lunar respectively. The former facet is irregularly 
oblong with a sigmoid curvature in dorso-palmar section. Transversely, 
it is concave dorsally and plane or slightly convex toward the palmar 
margin. The lunar facet is convex, becoming slightly concave dorsally. 
On the median side there is an irregularly quadrilateral, almost plane facet 
for the trapezoid. The facet for the unciform is confined to the dorsal 
margin of the magnum, unlike its position in Thylacynus. It is quite 
irregular in shape, with an uneven undulating surface. Distally, there is 
a broad triangular, concave facet for the third metacarpal. 
The unciform is partially broken and the facets for the magnum and 
cuneiform are incomplete. In shape it seems to have been irregularly 
tetrahedral. Distally this element bears a broad triangular facet for the 
fourth and fifth metacarpals. The surface for the fourth metacarpal is con- 
cave dorso-palmarly and plane transversely. That for the fifth metacarpal 
is also concave dorso-palmarly, but is convex transversely. 
The metacarpal of the pollex is missing, but, judging from the size of 
