120 PROFESSOR OWEN ON THE GENUS DINORNIS. 
enables me to refer with confidence the sternum to that species, most probably to the 
same individual as the pelvis; and the comparison of the sternum with the femur 
described and figured p. 371, pl. 43. figs. 5, 6, 7, Zool. Trans. vol. vii., gives the fol- 
lowing proportions of length:—sternum 6 inches 6 lines, femur 7 inches 6 lines. The 
length of the sternum is here taken from the fore border of the coracoid groove to the 
tapering hind end, which is all but entire. 
The inferiority of size of the sternum figured in vol. iv. pl. 4. figs. 5-8 to the sternum 
of Aptornis defossor is greater than that of the femur of Aptornis otidiformis as com- 
pared with that of Apt. defossor. But the relative size of the smaller sternum to the 
femur of Aptornis otidiformis is more like the relative size of the sternum of Aptornis 
defossor to the femur of that species than is the relative size of the smaller sternum to 
the femur of Notornis. Seeing therefore, in the two existing Rallines here compared, 
that as the wings decrease and the legs increase in size the sternum becomes shorter in 
proportion to the femur, I am inclined to believe that the smaller sternum (Trans. Zool. 
Soe. vol. iv. pl. 4. figs. 5-8) has belonged to Aptornis otidiformis rather than to Notornis. 
This view derives further support from the fact that, with the decreasing relative size 
to the femur, there is a progressive simplification of the sternum in the recent Rallines 
(Lribonyx, Ocydromus), by which the still more simple type of the bone in Aptornis 
defossor is approached. ‘The slender lateral processes, for example, in Tribonya ven- 
tralis come off immediately behind the costal border, diverge and extend backward 
beyond the body of the bone, with slightly expanded terminations. In Ocydromus 
australis the slender lateral processes come off at some distance from the costal borders, 
near the hind part of the body of the sternum, are consequently much shorter, and 
have no terminal expansion. The keel, which is well developed in Tridonya ventralis, 
is much reduced in Ocydromus australis’; it is almost obsolete in Aptornis defossor. 
As the wings of Notornis are relatively less than those of the Weka, and the legs 
relatively larger, it is not likely that the sternum would bear the same proportions of 
length to the femur as the sternum figured in tom. cit. pl. 4. figs. 5-8 bears to the 
femur figured in tom. cit. pl. 2. fig. 3. Whether, however, the sternum of the smaller 
species of Aptornis would be shorter in proportion to the femur than it is in Aptornis 
defossor may be questioned. 
Demonstration on this point still waits the acquisition, so long desiderated, of the 
entire skeleton of Notornis. 
This, at least, is certain, that the larger sternum, belonging to Aptornis defossor, 
repeats all the generic characters of that of which the reference oscillates between 
Aptornis otidiformis and Notornis mantelili. 
As in it, the present larger sternum is of an elongate triangular form, the base 
anterior and concave, the curve of the emargination being interrupted by the pair of 
1 Descriptive Catalogue of the Osteological Series, Mus. Coll. of Surgeons, 4to, 1853, p. 238. no. 1280 
(Brachypterye). 
