SCOTT: TOXODONTA OF THE SANTA CRUZ BEDS. 217 
and most slender of the series, though there is no great difference in 
length between any of the three members, and is considerably more 
slender in proportion to its length than in Nesodon , which it otherwise re- 
sembles in shape and connections. Metatarsal III is much heavier and 
somewhat longer than mt. II, and in shape and proportions is very similar 
to that of Nesodon , except that the distal broadening of the shaft is more 
gradual. Metatarsal IV is also very stout, much heavier than mt. II ; in- 
deed, the proximal end has as great a dorso-plantar diameter as that of 
mt. Ill, but is a little narrower transversely. 
The phalanges of digit II are much more reduced than those in the 
corresponding digit of the manus and are considerably smaller proportion- 
ately than those of Nesodon ; they are short, narrow and thick, not de- 
pressed, and the small ungual is not cleft. In digit III the phalanges are 
very much larger than in either of the lateral digits and thus make the 
median toe greatly exceed both the laterals in length. Nearly all of this 
excess is due to the phalanges, for the three metatarsals differ but little in 
regard to length and, relatively, these phalanges are longer and narrower 
than in Nesodon. Compared with those of the median digit of the manus, 
they are slightly longer, broader and more depressed and flattened. The 
phalanges of digit IV, as in Nesodon , considerably exceed those of digit 
II in size. 
Restoration (PI. XII, fig. i). — In its general appearance and propor- 
tions, the skeleton of Adinotherium differs very considerably from that of 
Nesodon , being not only a much smaller, but also a much lighter animal, 
and lacking entirely the massiveness of structure which characterizes 
Nesodon. The proportions of the skull, as to length and dorso-ventral 
height, do not differ materially in the two genera, but in Adinotherium 
the neck is slightly shorter, the length of the skull being taken as a stand- 
ard, and much lighter, the processes of the cervical vertebrae being rela- 
tively shorter and more slender. The trunk, on the other hand, is pro- 
portionately longer and the vertebral column has quite a different appear- 
ance, owing partly to the lesser degree of curvature in the anterior region 
of the thorax and still more to the shorter and more slender neural spines. 
The changing length of the spines quite accurately compensates for the 
curvature of the column, so that their free ends reach nearly the same 
horizontal plane and the profile of the back must have been almost 
straight in the living animal. This is in very marked contrast to the 
