368 PROFESSOR OWEN ON THE GENUS DINORNIS., 
divisions diverging to the upper end of the condylar risings (ib. w, y), but subsiding 
before attaining these. 
At the lower part of the pretrochanterian surface, midway between the head and the 
ectotrochanterian tuberosity, is the rough surface, partly prominent, partly depressed 
(Pl. LX. fig. 1, s), which seems to represent the small trochanter in Mammals. 
The rotular cavity or channel (ib. fig. 1,4), 2 inches across and 13 inch in depth, 
shows no trace of the rising marked in that part of the femur of Dinornis giganteus’. 
The anterior intercondylar ridge dividing the rotular fossa (¢) from the intercondylar 
one (Pl. LXI. fig. 1, v, v') is sharp. The intercondylar fossa is partially divided into two 
depressions, the inner one (ib. v) being the deepest, the outer one (v') the largest, 
These are divided from the popliteal cavity (Pl. LXI. fig. 1, z) by the post-intercondylar 
ridge (ib. w), which is well marked, but shorter, thicker, and more rounded than the 
anterior one (Pl. LX. fig. 2, 7’), 
The entocondylar articular surface (ib. w’) has the usual relative size and shape’. 
The ectocondylar surface for the tibia (ib, #) is comparatively small, measuring 
1 inch 9 lines by 1 inch in extent; it is continued over the ridge-like posterior pro- 
jection of this part of the condyle to that on the concavity or groove for the head of 
the fibula (Pl. LXI. fig, 1, y), which groove is feebly divided into an upper (y') and 
lower (7) tract, 
The popliteal space (Pl. LXI. fig. 1, z) has the usual dinornithic depth, shape, size, 
and oblique direction. It is rugous; and some small foramina at its deepest part are 
the sole representatives of a pneumatic system, though probably related only to the 
transmission of vessels. 
The contrast is striking, in placing by the side of the above-described bone the femur 
of any of the species of large existing Struthious birds, in regard to every indication of 
the strength and vigour of application of the hind limbs. The chief results of the 
comparison of the femur of Dinornis with that of Struthio were recorded in the original 
Memoir on the first received bones from New Zealand®. But the femur of the Emu 
(Dromaius), though still smaller than that of the Ostrich in comparison with the 
gigantic species of Dinornis, is less different in shape. The shaft of the bone is 
rounder than in the Ostrich; but the antero-posterior diameter of that part is less 
than in Dinornis, There is no trace of the bifurcate ridge on the fore part of the 
shaft, and very feeble indications of “line aspere” on the back part; of the tube- 
rosities there developed in Dénornis no rudiment eyen is present in existing Stru- 
thionide. The medullarterial canal is very minute in Dromaius, as in other pneumatic 
femora; and the associated large air-hole at the back part of the upper end of the 
femur significantly differentiates Dromaius, as it does the other large existing Stru- 
thionide, from Dinornis. The head is sessile; one cannot predicate a cervix in the 
1 Trans. Zool. Soc. vol. iii. pl. 44. fig. 2, 7. 
2 Th, ib, pl. 46. fig. 3, ¢ (Dinornis casuarinus), 5 Tb. ib. (1843) p. 249. 
