SCOTT: TOXODONTA OF THE SANTA CRUZ BEDS. 1 63 
Metacarpal IV is not an exact counterpart of me. II, even disregarding 
the different shape of the proximal ends, being shorter, heavier and 
straighter, but the difference of length is compensated for by the fact that 
the head of me. II rises much higher into the carpus than does that of 
me. IV, while their distal ends are in nearly the same horizontal line. 
In me. IV, the proximal end is overlapped by the head of me. Ill, with 
which it articulates by two convexities which fit into the concave, oval 
facets on the ulnar side of me. Ill already described and by a large, 
convex surface proximal to these. On the ulnar side of the head is quite 
a large facet for the vestigial me. V. The shaft is rather heavier and 
straighter than that of me. II, but is of similar trihedral cross-section, and 
the distal trochlea is narrower and its proximal border on the dorsal face 
is less regularly curved, being higher on the mesial and lower on the 
external side. Metacarpal V is not represented in any of the collections, 
but that it was normally present is demonstrated by the facets on the 
pyramidal, unciform and me. IV. Ameghino has figured it in the 
closely allied, if not identical, genus Xotoprodon (’94/, 246, fig. 1) as a 
small, irregular nodule, articulating with the three bones just mentioned. 
In Toxocion the metacarpals have assumed elephantine proportions, 
being relatively shorter and very much broader than those of Nesodon. 
Metacarpal II articulates extensively with the magnum, but does not 
overlap the head of me. Ill so much as in the Santa Cruz genus. The 
keel of the distal trochlea is much reduced and in me. Ill is hardly dis- 
tinguishable. The presence of the rudimentary me. V is indicated by the 
facets for it upon the adjoining bones, and, as in Nesodon , it is extended 
proximally to a contact with the pyramidal, but is shifted more to the 
palmar side than in that genus. 
The phalanges of the manus of Nesodon are very incompletely known 
and the few specimens which the collections contain may be most advan- 
tageously described in connection with those of the pes. 
The pelvis (PI. XXIV, fig. 1) is broad and heavy, but of no great 
antero-posterior length. The ilium is relatively rather small ; the neck 
is short and laterally compressed and has obscurely marked borders, so 
that the usual trihedral shape of the peduncle is hardly apparent ; there 
is no ilio-pectineal process. The anterior expansion or plate of the ilium 
is of only moderate width and is but slightly everted. The shape of the 
crista is not satisfactorily shown in any of the specimens, but apparently 
