2 12 
PATAGONIAN EXPEDITIONS I PAL/EONTOLOGY. 
relatively shorter than that of Nesodon, but otherwise resembling it, 
though the proximal surface for the ulna is somewhat less deeply 
concave. 
There is more difference between the two genera in the shape of 
the pisiform than in any other carpal element. In Adinotherium, the 
proximal end of the pisiform is relatively broader and much more 
depressed and the facets for the ulna and pyramidal are relatively 
smaller ; the tuber is more slender and has a straighter inferior border, 
while the free, or distal, end is less thickened and rugose. It should be 
added, however, that there is considerable difference among various indi- 
viduals in the shape of the pisiform. Its character in some specimens 
approaches that of Nesodon , but I have no means of determining whether 
this variation is specific or merely individual. 
The trapezium is not preserved in any of the examples of the manus, 
but was no doubt present. The trapezoid differs in hardly any appreci- 
able way from that of Nesodon ; it is a little broader in proportion to its 
proximo-distal length and contracts to a narrow palmar edge, while 
the distal facet for me. II is more concave transversely, less so palmo- 
dorsally. The magnum differs from that of Nesodon chiefly in its reduced 
dorso-palmar diameter and in the very small size of the palmar rugosity. 
Like the trapezoid, the magnum also narrows more to a palmar edge and 
the facets are all correspondingly narrowed. The trapezoid facet is 
relatively larger and the sulcus which invades it from behind is much 
smaller. The unciform, like most of the other carpals, is proportionately 
lower and wider than in Nesodon and has a narrower palmar projection. 
Of the two proximal facets, that for the lunar is not reflected down upon 
the palmar side so far as in the latter genus and that for the pyramidal 
has no such palmar extension. The same is true of the facet on the radial 
side for the process from the head of me. Ill, this surface being 
confined to the dorsal moiety of the unciform, instead of extending over 
the whole dorso-palmar diameter of the bone, as it does in Nesodon. 
As in Nesodon , the metacarpus consists of three functional mem- 
bers, me. II, III and IV, and a vestigial representative of me. V. The 
functional elements, except for their very much smaller size, closely 
resemble those of Nesodon , but are proportionately somewhat more 
slender. Metacarpal II reproduces that of the last-named genus almost 
exactly, but the projection from the palmar side of the head is decidedly 
