Cope.} 402 [April 15, 
Note on the Structure of the Posterior Foot of Towodon. By HE. D. Cope. 
The position of the genus Tozodon in the system of Mammalia, is a ques- 
tion upon which few authorities have expressed positive opinions, and 
which is generaily regarded as still an open question. In the lack of cer- 
tainty on the subject, a separate order, the ‘‘ Toxodontia,”’ has been pro- 
posed for its reception. It is known that the genus is ungulate, but 
the opinions of authors are much divided as to its relations to the three 
principal orders included under that head. Resemblances to the Probdos- 
cidea have been detected, but Professor Gervais (Comptes Rendus, 1878), 
asserts that there is a close resemblance to the genus Hippopotamus in the 
structure of the posterior foot. 
Having come into possession of remains of Towodon, which include the 
greater part of the skeleton, I make a few observations on the affinities 
suggested by the posterior foot, the only portion just now accessible in my 
collection. The caleaneum and astragalus have been more or less imper- 
fectly figured by De Blainville and Burmeister, but no one has, to my 
knowledge, represented the entire foot. The calcaneum is rather short and 
stout, and its external convex tuberosity is of unusual size. Its articular 
surface is divided into two subequal parts, the internal of which sup- 
ports the astragalus, the external the fibula. Thus the fibular articulation 
is of unusual size. The cuboid facet is on the inferior face of the ex- 
tremity of the calceaneum, thus looking directly downwards when the bone 
is prone. In order to articulate with the remainder of the foot, the calcaneum 
must have been inclined upwards and forwards at an angle of 45°, and the 
cuboid inclined downwards and forwards at a similar angle. That the axis. 
of the astragalus had the latter inclination is proven by the fact that the 
superior plane of the sustentaculum lies at that angle to the axis of the re- 
mainder of the calcaneum. The great convexity of the external tuberosity 
for the astragalus will also permit of such a position for the astralagus. 
The navicular facet of the astragalus is plane and truncates the bone 
somewhat inferiorly as well as distally, so as to present in the same 
way as the cuboid. There is probably no cuboid facet. I have 
not seen the cuneiform bones. The metatarsals and phalanges are robust 
and rather short. The distal keels of the former are posterior and rudi- 
mental. Their proximal extremities have a small lateral tarsal facet as 
well as the principal one. The median digits are of unequal length, and 
the lateral ones are much shorter, but robust. Whether there are four or 
five digits I cannot definitely ascertain. 
The above characteristics are very significant. They at once refute any 
supposition of affinity to the Artiodactyla, whether suilline or ruminant. 
The form of the astragalus and wide fibular condyle of the calcaneum, 
opposes the reference of the genus to the Perissodactyla. On the other 
hand, all the characters of the feet thus far adduced, are found in the Pro- 
boscideu. They are not only those of that order, but they are carried to a 
degree of exaggeration, as though Toodon represented a high grade of 
