122 FEMUR PROBABLY OF THYLACOLEO ; 
The following papers were read :— 
ON A FEMUR PROBABLY OF THYLACOLEO; 
BY 
C. W. DE, VIS, “WEA 
(Read on 6th August, 1886.) 
(PLATES III. AND IV.*) 
ANY part presumptive of the skeleton of Thylacoleo 
deserves attention; if it be one with a promise to throw 
light on the mystery of the animal, so much more is it 
welcome, and few relics are better able to do so than a well 
preserved femur. Such is the fossil under observation, but 
since it comes before us with a pretension like this and is, 
as usual with those from the Darling Downs, an isolated 
bone, it behoves us to ascertain with proportionate care 
whether there are reasonable grounds for believing it to 
have been the growth of Thylacoleo. 
Fortunately we have not far to seek for a sufficient token 
of its marsupiality; we find it in the transversely-undulated 
surface of the inner condyle. But the presence here of a 
longitudinal groove formed by such undulation may be 
thought to prove too much for our purpose since we recog- 
nise it as a modification restricted (in its present degree) 
to the kangaroos and related evolutionally with the faculty 
of leaping. The suspicion germinated that the fossil is the 
femur of a kangaroo is, however, quelled at once by the 
absence of the characteristic cavity above the condyle, by 
that also of the quadratus tubercle, by the depression of the 
great trochanter, and by the whole facies of the bone. 
The kangaroos (Hypsiprymnide inclusive) being disposed 
of, we might proceed to compare our fossil with the femurs 
of the remaining families, but the progressive steps of 
further elimination would be tedious to read, though they 
* The figures represent the bone reduced in the proportion indicated, 
1€., 135 2 206. 
