178 PROFESSOR OWEN ON THE GENUS DINORNIS. 
In Dinornis the twenty-fourth vertebra (3rd sacral), answering to the twenty-eighth 
vertebra of Struthio (Mivart’s ‘ lumbar vertebra’), differs in presenting an unmistakably 
rib-like pleurapophysis, although unanchylosed. The fourth sacral in Dinornis is the 
first which may be said to “ present no indication of a rib,” and which would be entitled 
to the term “lumbar,” according to such character. I view, however, the parapophysial 
element of this transverse process as more probably the serial homologue of the cervical 
part of the preceding pleurapophysis. 
With this explanation the neural arch of the fifth sacral vertebra in Dinornis, as in 
Struthio, advances and crosses the interspace between its own and the preceding cen- 
trum; and the thirteenth vertebra is that in which the arch resumes its normal con- 
nexions. ‘Thus the interlocked part of the sacrum in Dinornis is more extensive than 
in Struthio, and relates to the heavier mass which the pelvis had to transmit upon the 
femora. 
The antacetabular part of the sacrum (Ist to 6th vertebra in Déinornis) is relatively 
shorter and broader than in Struthio; the postacetabular part is still broader in pro- 
portion to its length; and this part is shorter than the antacetabular part, instead of 
being, as in Struthio, longer. 
More striking differences are presented by the pelvis as a whole. The antacetabular 
part of the ischium is relatively longer; the postacetabular part is shorter, but much 
broader in Dinornis than in Struthio: the greater relative breadth of the entire pelvis 
would seem to relate to the larger proportional size of the egg in Dinornis. 
The ischium is shorter and deeper than in Struthio: it unites with the ilium 
anteriorly to bound there the ischiadic notch, which remains open posteriorly, as in 
Struthio, and is not circumscribed by a second terminal union of the ischium with 
the ilium, as in Dromaius. The obturator interspace, closed behind, as in Struthio, by 
ischial confluence with the pubis, and having its fore part defined by the descending 
process of the ischium, is much narrower in Dinornis, as in Apteryx. The pubis does 
not send off so long and well-defined a ‘ pectineal process’1, as in Struthio; its body 
extends backward parallel with the ischium, slightly concave downward, and ter- 
minates in the vertical expansion joining the ischium without being continued down- 
ward and forward to meet its fellow at the symphysis, a structure which is peculiar, 
among birds, to the genus Struthio. 
The type of the pelvis in Dinornis is that of the Apterya, not of the Emu or Cas- 
sowary; it differs therefrom in less marked modifications than from the pelvis in 
Struthio and Rhea. 
The number of terminal sacral vertebre in Dinornis maaimus, answering to those 
defined as ‘ sacro-caudals’’, is four. The last of these in Dinornis is the thirty-ninth of 
the vertebral series; in Struthio it is the forty-sixth. : 
1 For this process in Apterya australis, see Trans. Zool. Soc. vol. ii. p. 291. In the two skeletons of the 
smaller Kivi (Apteryx Owenii, Gd.) I haye found ossification extending along the ligament attaching the 
pectineal process to the last sacral rib. 2 Mivart, ut supra, p. 426, fig. 62. 
