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PATAGONIAN EXPEDITIONS ! PALAEONTOLOGY. 
and shorter proximo-distally ; the proximal end has a strongly convex 
facet for the radius, which projects dorsally and overhangs the anterior 
face of the carpal. The contact with the pyramidal is entirely distal, the 
two bones being quite widely apart at the proximal end, as might be 
expected from the corresponding surfaces on the ulna and radius. Dis- 
tally, the lunar rests upon the magnum and unciform, more extensively 
upon the former, and the magnum facet differs from that in Nesodon in 
being more distal and less lateral, in consequence of which the two sur- 
faces meet at a more obtuse angle. The pyramidal is very much like 
that of Nesodon in form, except that the interno-distal angle is more pro- 
duced and tends to extend underneath the lunar ; it has quite an oblique 
position in the carpus, diverging proximally from the lunar, in accordance 
with the space between the distal facets of the ulna and radius. The 
surfaces for the ulna, pisiform and unciform are not particularly 
characteristic. 
The trapezium is a small, laterally compressed and scale-like bone, 
and, though it supports a functional pollex, it would seem to have had 
no connection with the scaphoid, as is also the case in Nesodon , in which 
me. I has completely disappeared. The trapezoid is quite different in 
appearance from that of the contemporary Toxodonta, being much higher 
proximo-distally in proportion to its width, and is closely interlocked 
with the magnum. The proximal end has an oblique facet for the sca- 
phoid and the distal portion of the radial side articulates with the trape- 
zium. The long axis of the magnum is oblique to that of me. Ill, inclin- 
ing downward and toward the ulnar side. The bone is much longer and 
narrower than in Nesodon and contracts proximally, so that the dorsal 
face has almost the shape of an inverted wedge, the truncation of which 
forms the narrow facet for the scaphoid. The lunar facet is far larger 
than in Nesodon and less lateral, more obliquely proximal in position 
and is quite convex. The magnum is not overlapped by the unciform, 
the facet for which on the fibular side is vertical and quite narrow. The 
distal end is also oblique, but sloping in the opposite direction, toward 
the radial side. The unciform, which is much the largest of the carpal 
elements, is higher and narrower than in Nesodon , with its principal 
diameter proximo-distal. The proximal end is unequally divided 
between the narrow surface for the lunar and the much broader one for 
the pyramidal ; the latter slopes steeply downward, making the external, 
