124 FEMUR PROBABLY OF THYLACOLEO ; 
posterior surface of the shaft at about the same relative 
distance from the lower (distal) end of the post-trochanterian 
fossa as in Sarcophilus. By this sudden curve of the ridge, 
the trochanter is rendered apparently more than usually 
prominent. In Phascolomys the ridge descends with a 
rather convex edge, much less obliquely (its directions in 
Sarcophilus being intermediate), and terminates low down 
on the inner edge of the hinder face of the shaft. The 
post-trochanterian fossa, vertical in the wombat, is in the 
fossil a little inclined, and were not this end of the bone 
inwardly curved the fossa would be even more oblique than 
in Sarcophilus. The great trochanter is, on its outer sur- 
face, regularly convex both transversely and longitudinally ; 
its anterior edge forms a continuous ridge, the proximal 
half of which is in advance of the distal and gaining promi- 
nence, folds a little over forwards and forms one of the 
distinctive features of the bone from an anterior point of 
view. The trochanter terminates distally with a feeble 
tumidity, as in Sarcophilus, but situated lower upon the 
shaft. The tubercle familiar to us in the wombat is con- 
spicuously absent. The trochanter, rising a little above the 
head, is more elevated and has a sharper apex than in 
Phascolomys, and in these respects resembles that of the 
recent carnivore, with which it further agrees in the separa- 
tion of its apical portion from its anterior base by a deep 
groove which is but faintly marked in Phascolomys. But 
the form of the base, as a single and well-defined eminence, is 
better conserved in the latter genus than in Sarcophilus, in 
which it is partially divided by asinuosity of the epiphysial 
suture. 
The summit of the anterior surface of the shaft beneath 
the neck is, in the wombat, rather deeply concave. Sar- 
cophilus and the fossil have in this part an equally moderate 
degree of concavity. They also present a similar oblique 
flattening of the inner foreside of the lower two-thirds of 
the shaft contrasting with its symmetrical convexity in 
Phascolomys. On the hinder surface, the pit immediately 
proximad of the inner condyle of Phascolomys, is not found 
in the fossil. The supracondylar concavity is shallower 
than in Sarcophilus, shorter than in Phascolomys. It is 
bounded on the inner side by an angular ridge rising from 
