peat geo] 
IV. On Dinornis (Part XVII.): containing a Description of the Sternum and Pelvis, 
with an attempted Restoration, of Aptornis defossor, Ow. By Professor OWEN, 
ERS. F.LS., &e. 
Read June 6th, 1871, 
[Puates XIV. to XVI.] 
THE nearly complete sternum and pelvis of Aptornis defossor about to be described, 
in addition to the evidences of that bird submitted to the Zoological Society in a 
former Memoir’, encourage me to attempt a restoration of the skeleton of the extinct 
species (Pl, XVI.), with which I propose to conclude the present Memoir. 
The sternum, figured of the natural size in Pl. XIV. figs. 2, 3, 4, presents a close 
family, if not generic, resemblance to that described and figured in my fourth Memoir 
on Dinornis*, with regard to which, recognizing in it unequivocal characters of a Ralline 
type, closely resembling that of the wingless Wekas (Ocydromus), but of much larger 
size, I had doubts whether to refer the bone to the Notornis (subsequently recognized 
as a still existent species), or to the still larger Aptornis otidiformis, which is most 
probably extinct. 
In Tribonyx ventralis the length of the sternum is 2 inches, that of the femur is 
2 inches 3 lines. In Ocydromus australis the length of the sternum is 2 inches, that of 
the femur is 2 inches 8 lines. In Notornis* the length of the femur is 4 inches 10 lines; 
in Aptornis otidiformis* the length of the femur is 6 inches 3 lines. The length of the 
sternum described p. 18, and figured in pl. 4. figs. 5-8, in Zool. Trans. vol. iv., is 
4 inches 6 lines, measured from the foremost part of the coracoid groove to the 
tapering hind end, which is not entire. I do not suppose, however, that the missing 
portion would exceed 6 lines in length; and it might probably be less, An addition of 
4 lines would make the sternum in question equal in length to the femur of Notornis, 
and 12 inch shorter than the femur of Aptornis otidiformis. I select the femoral 
bone of the hind leg for this test comparison, because it varies less in proportion to 
the trunk or general size of the bird than the more distal elements of the limb. A 
comparison of the metatarsus of Notornis with that of Aptornis instructively illustrates 
this principle’, 
The contiguity of the bones of Aptornis defossor here described, when discovered, 
2 On Dinornis, part xy., Trans. Zool. Soc. vol. vii, p. 353, 
3 Trans. Zool. Soc. vol. iv. p. 17, pl. 4, figs. 5-8. 3 Th. vol. iv. p. 12, pl. 2. fig. 3 
$ Tb. vol. iv, p. 10, pl. 3. fig. 3, 
5 ©On the Archetype and Homologies of the Vertebrate Skeleton,’ 8yo, 1848, p. 200, note, p, 202, 
VOL. VIII,—PART 111. September, 1872. U 
