AXIAL SKELETON OF THE STRUTHIONID^. • 31 



THE SACRAL VEETEBR^. 



The thirty-seventh, -eighth, and -oiinth vertebrae, or sacral vertebrae, must be so called 

 because they seem to correspond in position with the sacral vertebrae of the preceding 

 genera. They cannot, hovcever, be separated off from the vertebrae which succeed them 

 by any structural character, as can the vertebrae of Struthio and Bhea — as they all, as 

 in Dromceus, send out similar transverse processes to abut against the postacetabular 

 part of the ilium. 



THE SACRO-CAUDAL VERTEBRA. 



The nine, ten, or eleven vertebrae which succeed the sacral vertebrae, i. e. (in C. 

 galeatus) the vertebrae from i^xe fortieth to the fiftieth inclusive, are quite like those of 

 Dromceus. They gradually elongate as we proceed postaxiad; and their transverse 

 processes become successively wider axially. Their spinous process becomes successively 

 shorter and more and more inclined postaxiad. 



THE CAUDAL VERTEBRA. 



The eight or nine caudal vertebrae (the fifty-first to the fifty-ninth inclusive, in C. 

 galeatus) closely resemble the caudal vertebrae of Drotnwus ; but their transverse pro- 

 cesses and their postzygapophyses are not quite so much developed "as in that genus. 

 The pygostyle is like that of Dromceus, cylindrical and irregular, and looking as if made 

 of three small vertebrae ankylosed together (fig. 22). 



THE PELVIS. 



When viewed preaxially the pelvis quite resembles that of Dromceus, except that 

 (owing to the greater ventrad curvature of the postaxial part of the ilium) the ventral 

 surface of the sacro-caudal vertebrae comes more into view, and except also that the 

 concavity between the antitrochanteric and supratrochanteric processes is as great as in 

 Bhea. 



Viewed laterally, it only differs from that of Dromceus in that the dorsal margin of 

 the postaxial part of the ilium is still more convex, in that the preacetabular part of 

 the ilium is relatively greater, and in that the ischium and ilium may (as in C. galeatus) 

 ankylose together at their distal ends. 



Viewed dorsally and ventrcclly, the pelvis shows no noteworthy differences from that 

 of Dromceus, except that the inner surface of the ischium presents an antero-posterior 

 groove. 



The Ilium (figs. 22 & 26, il). 

 The ilium extends over from about twenty-three to twenty-five vertebrae, namely 



