Fl'EKODON AFKICANUS. — APTEEODON. 
225 
quite as higli as the top of the head. The lesser trochanter {Id.) is a large prominence 
united with the great trochanter hy a strong ridge, which forms the outer border of the 
deep digital fossa. The shaft is strongly compressed from before backwards, and broad 
from side to side ; on its outer side, about a third of its length from the proximal end, 
there is a rugose ridge representing a third trochanter (<.<.). The whole shaft is curved, 
the convexity being forwards. The distal articulation is very large. The rotular trochlea 
is narrow and extends far u[) the front of the hone, as in the femur of Uyeenodon 
figured by Scott (Journ. Acad. Nat. Sci. Philad. vol. ix. p. 523). The tuberosities are 
large and project strongly backwards, the inner (id.) rather the furthest ; they are 
separated by a broad and deep intercondylar groove. In its general form, particularly 
in the broad flattened shaft, the bone suggests that the animal may have been to some 
extent aquatic. It is possible that this femur may have belonged to Apterodon, or at 
least to the same animal as the humerus provisionally referred to Apterodon, since that 
bone also suggests possibly aquatic habits on the part of its possessor. The dimensions 
(in centimetres) of this specimen are : — 
Extreme length 23'2 
Uianieter of head 3T 
Width of proximal end 7 
,, mid-shaft 3‘2 
,, distal end t! 
M. 8887. Plaster cast of the above specimen. Made in the British Museum. 
(icniis APTEROEON, Fischer. 
[Bull. Soc. Geol. France, [3] vol. viii. (1880) p. 288.] 
1887. Dasyurndon, A. Andreae, Bericht Senckenberg. naturforsch. Gesellschaft, Frankfurt-a.-M. 
{). 125, pi. iv. 
The specimens described below agree closely with the figures of the teeth of 
JbasyuTodon given by Andreae. Unfortunately, Fisclier gives no figures of his 
Apterodon, tvhicli, from his description, differs a little from Dasyurodon ; but, since 
most authors regard the two names as synonymous, Apterodon is here adopted on 
the ground of priority. 
This genus is distinguished from Pterodon by the much slighter development of the 
cutting-blade of the lower carnassials, due to the smaller degree of compression of 
the cusps, and also to the much smaller size of the antero-internal cusp ; the talon also 
is relatively much larger. In these points Apterodon, in fact, seems to be intermediate 
between forms like Sinopa and Pterodon, just as the latter is intermediate between 
Apterodon and llycenodon, in the latter of which the talon is almost obsolete and the 
two anterior cusps form a sharp secant blade. 
