AND CLASSIFICATION OF THE FOSSIL REPTILTA. 
2G3 
border, 17 centims. from the proximal extremity, and not less than 6 centims. wide. 
There are some indications of a second, but slightly impressed, muscular attachment 
extending distally below this ridge. 
The difterences of this femur from the corresponding bone in the giant Salamanders 
of Japan are tliat in the living type the proximal half of the bone is rotated uy)ward 
at right angles to the distal end and that the condyles are not ossified; but the result 
is that the trochanteroid processes on the under side of the proximal end similarly 
define a shallow pit, comparable to that of the obturator pit in the fossil. The ridge 
which ascends from the internal condyle to the trochanter may be identical in both 
types, so that, allowing for the difference in ossification, there is more similarity than 
might have been expected between the two types. In Hatteria the bone is less 
compressed in the shaft, and has a much greater development of the iufero-anterior 
proximal trochanter. Sir R. Owen has already drawn attention to the Monotreme 
characters in the Anomodont femur. 
Ilumeviis of Titanosuchus ferox (Owen). (Plate 20.) 
The humerus is a strong bone approximating to the ordinary Dicynodont type, 
with both proximal and distal ends greatly expanded, but more nearly in the same 
plane than in smaller animals. It is 53 cenilms. long, nearly 30 centims. wide over 
the distal condyles, and slightly wider over the proximal end. The lateral outlines 
are concave, so that the transverse measurement over the middle of the shaft is 
reduced to 13 centims. The specimen exhibits a remarkable development of the 
distal condyles on the inferior aspect of the bone, which is unparalleled among other 
Reptilia, the vertical extension of the condyles in the middle of the shaft measuring 
about 18 centims., or fully a third of the length of the bone. On this postero- 
inferior aspect the outline of the condyles is sub-triangular, with the angles rounded 
and the superior border convex from side to side, and rising sharply from the slmft. 
The convexity of the condyle in this region is absent, and the proximal part of the 
surface, on which a filnrof matrix remains, appears to be flat. The thickness through 
the shaft in this region is about 14 centims. ; and the measurement is scarcely less 
through the globate radial condyle. The ulnar condyle is comparatively compressed, 
and not more than 7 centims. thick, but well rounded on the distal surface ; in the 
transverse direction a moderately wide and shallow concavity divides the smaller ulnar 
region from the large radial region. On the superior aspect of the bone this concavity 
is developed as a shallow triangular area, about I 5 centims. broad and as high, which 
is defined towards the radial side by a blunt ridge. The area is gently concave ; the 
surface external to the ridge is about 10 centims. wude and flattened ; the corre¬ 
sponding surface of the distal part of the shaft on the ulnar side is rounded convexly 
towards the lateral margin. Both lateral margins are sharp for some 10 centims. 
above the condyles, but the ridge is narrower, sharper, and more convex in its lateral 
