502

2

met with a prompt and hearty response. The Trustees of the Australian Museum
directed the unique bird's bone to be moulded, and they forwarded to me a plaster cast.

Mr Krefft was so good as to have three photographs taken of the fossil ;- one showing
the back view of the bones, three fifths the natural size ; the two others the front views
of the proximal and distal halves of the bone, of very nearly the natural size.

With these evidences a satisfactory comparison can be made of the Australian fossil
with the femora of other large wingless birds, both recent and extinct.

The bone is the right femur (Pl. C.). It measures 11 inches 6 lines ; and there may
be an inch more of this dimension lost by the abrasion to which both ends have been
subject. The middle third of the shaft is entire, and shows its natural form and
surface; the breadth of this part is 2 inches 6 lines ; the antero-posterior thickness
does not exceed 1 inch 7 lines (ib. fig. 2). The extreme breadth of the upper end
is 5 inches 3 lines, that of the lower end is 5 inches ; but these latter dimensions fall
short, probably by half an inch, of those which the unabraded or entire femur would
have yielded.

Of the femora of Dinornis I selected for comparison that of Din. elephantopus 1, as
nearest to the present fossil in regard to length (13 inches) ; the breadth of the shaft is
the same, or, in the largest examples of D. elephantopus, exceeds only by 2 lines that of
the Australian femur.

But the shaft of the bone in Dromornis is compressed from before backward ; its trans-
verse section is a narrow oval (ib. fig. 20, while that of the Dinornis is a fuller and less
regular oval (ib. fig.3) from the greater proportion of fore-and-aft breadth of the shaft.
The back part of the shaft of Dromornis australis, besides being less convex transversely,
is devoid of the strong ridges and tuberosities which characterize that part in all the
species of Dinornis ; in this respect, as in the shape of the transverse section of the
femoral shaft, Dromornis resembles more that bone in the Emu (Dromaius ater). The
bifurcate anterior muscular ("intervastal") ridge which characterizes the fore part of
the femoral shaft in Dinornis elephantopus, as in other species of that genus, is not
defined on that part of the femur of Dromornis. The longitudinal ridge, descending
from the pretrochanterian ridge to the ectocondylar expansion, is traceable in the cast,
but is less strongly marked than in Dinornis. The mutilation of the prominent parts
at the proximal end of the femur begets a reticence in drawing conclusions from
apparent differences ; but some were evidently inherent in the original when entire.
The periphery of the head of the femur (d) is not constricted so as to give the appearance
of a "neck" as it is in Dinornis.

The trochanterian part of the articular surface (c) is more horizontal, does not ascend
as it recedes from the head, in Dromornis. so far as the trochanter (f) is preserved in
the cast, and appears in the photographs, it does not rise above the level of the head (a)
of the femur, and seems not to have risen, when entire, so much above it, as in Dinornis ;
the lay of the trochanterian articular tract agrees with these indications of the remain-

1 Pl. LVI. fig. 1.