354 PATAGONIAN EXPEDITIONS: PAL/EONTOLOGY. 



in Sarcophilus and Prottyilacynns. In shape, the scaphoid resembles 

 more closely that of Sarcophilus than the corresponding element in 

 Thylacymts. 



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 Thylacymts (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 Thylacyrms. It is irregularly 

 oblong in form, with a B-shaped 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 SarcopJiilus rather than the correspond- 

 ing element in Thylacymts. 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 Thylacymis. 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 



