32 MR. ST. GEORGE MIVART ON THE 
from the twenty-fifth or twenty-sixth to the end of the sacro-caudal vertebre. Its main 
peculiarities have been already noticed. 
Tue Puss (figs. 22 & 26, p). 
This bone may end freely at its distal end; it may, on the contrary, ankylose distally 
(as in C. galeatus) with the distal end of the ischium. 
Tue Iscurum (figs. 22 & 26, 7). 
The ischium may ankylose distally with the ilium, as in C. galeatus; it may, on the 
contrary, end freely, as in C. bennettii, where it extends postaxially beyond the post- 
axial extremity of the ilium. 
THE VERTEBRAL RIBS (fig. 21). 
These ribs are eleven or twelve in number, according as there are two or three dorso- 
lumbar vertebrae. The jist four are not united to sternal ribs; but to these succeed 
jive which are so connected. Finally, there are at least two, more postaxially placed, 
which end freely at their distal extremities; and there may be, as in C. australis, three 
such ribs. 
Uncinate processes may be altogether absent, as in the specimens of C. australis and 
C. bennettii. There may be, however, three such processes on each side, attached 
either to the sixth, seventh, and eighth, or to the seventh, eighth, and ninth ribs 
respectively. 
_ The vertebral ribs are flatter and broader than hitherto, and have a different twist. 
Those postaxiad to the third or fourth rib develop a blunt postaxially developed pro- 
cess, the process being situated near the proximal end of the shaft of each rib. Each 
rib (proceeding distad from the junction of the tuberculnm with the capitulum) is bent 
with its convexity preaxiad. More distally its convexity is postaxially directed. The 
ribs are more like the ribs of Dromeus than they are like the ribs of any other of the 
existing Struthionide ; but they are not so curved, and proceed more directly ventrad. 
THE STERNAL RIBS (fig. 21). 
These bones present no marked differences from those of Dromeus, save that they 
increase somewhat more gradually in length postaxiad. ‘The first joins the fourth or 
fifth vertebral rib, and belongs to the twentieth vertebra. The fifth may be twice the 
length of the first, or it may not reach the sternum. 
