Ne) 
72 PROFESSOR OWEN ON THE GENUS DINORNIS. 
eo 
“ well-marked ridge,” extending down the back part of the shaft, and inclining to ter- 
minate in the border of the inner condyle’, is repeated in the present species. In 
Dinornis the corresponding ridge is more median or even tends toward the outer side of 
the back surface of the femoral shaft, and ends abruptly in a tuberosity, usually one of 
a pair, at the lower third of the shaft, from the innermost of which extends the ridge to 
the inner condyle. This condyle in Dinornis does not reach so low as the outer one; 
and the terminal distal line is oblique, indicative of the greater angle at which that end 
diverges from the hip-joint to rest on the tibia of the robuster-bodied bird. In Apé. 
defossor, as in Apt. didiformis, the inner condyle more nearly equals in vertical extent 
the outer one, yet in a somewhat minor degree in the larger species. In both, the fore 
part of the two condyles is less prominent, and the rotular groove less deep, than in the 
femur of Dinornis?. The head of the femur is more truncate or depressed in Aptornis, 
through the relatively larger size of the ligamentous pit, than in Dinornis. 'The lower 
part of the head is more produced downward in Apfornis; and a short. ridge from the 
under and back part of the head (Ap¢. otidiformis), or of the neck near that border of 
the head (Apt. defossor) (Pl. XLIII. fig. 6), extends downward and rather backward for 
6 or 8 lines. Of this ridge there is no trace in Dinornis. A broader parallel ridge or 
rising extends about the same distance from along the back part of the supracervical 
articular surface: this extension from the head of the femur is more convex from 
before backward in Aptornis than in Dinornis. Of the pneumatic fossa, which in some 
species or individuals of Dinornis breaks the surface below the back part of the supra- 
cervical surface, there is no trace in either species of Aptornis. 
For the characters of the femur of Aptornis as compared with that of Cnemiornis, 
reference may be made to Trans. Zool. Soc. vol. y. p. 400, pl. 65. They are as well 
marked in Apt. defossor as in Apt. otidiformis. 
Tibia —The importance of such distinctive characters as “the tibial half of the 
proximal articulation is broader from behind forwards than transversely,” ‘the anterior 
ridge at the proximal end [‘ procnemial ridge’] is nearer the middle of the bone,” 
‘“‘the more rounded or less angular inner side of the shaft,” ‘ the proportionally greater 
antero-posterior thickness of the shaft,” “the deeper posterior notch between the distal 
condyles,” “* the more compressed and more backwardly produced inner condyle,” could 
not be fully estimated in the solitary tibia of the smaller species first described*. In the 
absence of a femur or of a tarso-metatarsal bone to match this tibia, I could only venture 
to affirm that “it unequivocally established a fourth species of cursorial bird” in the 
series of tibie first received from New Zealand. ‘The subsequent acquisition of the 
femur, the “ tarso-metatarsal’’*, and the skull of the Dinornis otidiformis of 1843 
impresses one instructively with the value of such seemingly insignificant modifications 
1 Trans. Zool. Soe. vol. iv. p. 10. 
* In my fourth Memoir, Trans. Zool. Soe. yol. iv. p. 11, nine lines from top, for “‘ more” read “less”. 
3 Trans. Zool. Soc. vol. iii. p. 247, pls. 25 & 26. fig. 5. * Tb. vol. iv. pl. 3. 
