382 PROFESSOR OWEN ON THE GENUS DINORNIS. 
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 bone, 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 (Pls. LXII. & LXIII. fig. 1). 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 (Pl. LXIII. 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 un- 
abraded or entire femur would have yielded. 
Of the femora of Dinornis I have selected that of Din. elephantopus’, 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 (Pl. LXIII. fig. 2), 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 (vol. vii. pl. 43. fig. 1), as in other species 
of that genus, is not defined on that part of the femur of Dromornis (Pl. LXII. fig. 1). 
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 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 Trans. Zool. Soc. vol. iy. (1856) p. 149, pl. 43. fig. 1. 
