PEOFESSOB OWEN ON THE FOSSIL MAMMALS OF AUSTEALIA. 
559 
have supported the view first suggested by the flattened form of the femur next to be 
described, if more instructive characters had not been shown deducible from the pelvis 
in question. 
The ilia, though not quite entire along the “ labrum ” (Plate XLYII. figs. 1 & 2, c), 
are sufficiently so to support the inference that they were short, broad or expanded, with 
a flattened surface rather than a fossa, directed heemad or downward, and in a minor 
degree forward. Such a lamelliform ilium is not presented by any existing genus of 
Marsupial, but is found, besides the Proboscidians, in Megatherioids, Sloths, Apes, and 
Man. 
From the Elephant’s the ilia of the present species differ in the much less production 
of the augle terminating in the antero-superior spine ( a , a), which, in Proboscidians, 
extends outward and bends down in an almost hooked form to near the parallel of the 
acetabular outlet. 
In the Megatherium and Mylodon the ilia are proportionally more expanded and 
outwardly extended than in the Elephant. The ilia of the Sloths ( Brctdypus , Cholcepus ) 
come nearer to the proportions of those in Plates XL VII. ; but the antero-superior angle 
is rounded off, and the position and aspect of the iliac planes are different. There is, 
however, a more marked, definite, and weightier distinction between the present pelvis 
and that of other Mammals with expanded lamelliform ilia. Leaving the human and 
simial pelves out of the comparison, that of the Elephant includes four sacral vertebrae, 
and the Sloths, both arboreal and terrestrial, have the sacrum unusually prolonged to 
effect the second junction with the innominate bones at the ischial tuberosities, thus 
converting the “ great sciatic notch ” into a foramen. 
In the present pelvis the sacral vertebrae are but two in number. Now this, as a rule, 
is the number to which the sacral vertebrae are restricted in Marsupialia ; and it strikes 
me as the more significant of the affinity, so indicated in the present pelvis, because it 
is associated with a modification of the ilium which, in the placental series, goes with at 
least double that number, and commonly with many more sacral vertebrae, five or six, 
e.g., in the Sloths and Megatherium, and as many as eleven vertebrae anchylosed in a 
mass in the Mylodon. A still more decisive mark of Marsupial affinity in the pelvis in 
question is the evidence of an ilio-pubic process (Plate XL VII. fig. 1, e, e) ; and this also 
points to the particular family of Marsupialia to which the large quadruped under con- 
sideration is more nearly related. Only in the Kangaroos is this process so developed 
as to be subject to such violence as has broken it away on both sides of the present 
pelvis. In all other Marsupialia it is indicated, if at all, by a mere tuberosity. The 
concurrence, therefore, of a bisegmental sacrum with the ilio-pubic process decides me 
to restrict further comparison with the pelvis of the Kangaroos {Macropus). 
I take the difference of form of the iliac bones, which is very great, between Macropus 
and Diprotodon — for if we arrive at the Marsupial genus with a diprotodont dental for- 
mula by the pelvic route we may be absolved of rashness in drawing the obvious con- 
clusion — to depend on the corresponding differences in the mode of locomotion deducible 
mdccclxx. 4 G ^ 
