[ 119 ] 



IV. On DiNORNis (Part XVII.) : containing a Bescrijttion of the Sternum and Pelvis, 

 with an attempted Restoration, of Aptornis defossor, Ow. By Professor Owex, 

 F.B.S., F.L.S., &c. 



Head June 6th, 1871. 



[Plates XIV. to XVI.] 



The nearly complete sternum and pelvis of Aptornis defossor about to be described, 

 in addition to the e\'idences of that bird submitted to the Zoological Society in a 

 former Memoir', encom-age me to attempt a restoration of the skeleton of the extinct 

 species (PI. XVI.), with which I propose to conclude the present Memoir. 



The sternum, figured of the natural size in PI. XIV. figs. 2, 3, 4, presents a close 

 family, if not generic, resemblance to that described and figured in my fourth Memoir 

 on IHnornis^, 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 stiU 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 pi. 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 1^ 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, 



' On Dinomia, part xv., Trans. Zool. Soc. vol. vii, p. 353. 



» Trans. Zool. Soc. vol. iv. p. 17, pi. 4. figs. 5-8. ^ lb. vol. iv. p. 12, pi. 2. fig. 3 



' lb. vol. iv. p. 10, pi. 3. fig. 3. 



' ' On the Archetype and Homologies of the Vertebrate Skeleton/ 8vo, 1848, p. 200, note, p. 202, 



VOL. viii. — PAKT III. September, 1872, u 



