38 



MR. ST. GEOEGE MIYAET ON THE 



THE DORSAL \T;RTEBR.E. 



These vertebrae, the seventeenth, eighteenth, nineteenth, and twentieth, differ from the 

 dorsal vertebrae of all other Struthionidse in the great and the equal development of 

 their neural spines, as also in the great relative axial extent of their diapophysial pro- 

 cesses. In them the hjpapophysis gradually diminishes postaxially in size, becoming 

 quite rudimental in the nineteenth vertebra. The twentieth vertebra has the ventral 

 suj-face of its centrum axially grooved. The last two dorsal vertebrae may be slightly 

 ankylosed together ventrally. 



THE DORSO-LUMBAR VERTEBRAE. 



These vertebrae (the twentg-first to the twenty-fourth inclusive) are more in number 

 than in any other of the Struthionidae. They all have equally high neural spines ; and " 

 these are equal in height to those of the dorsal vertebras ; also, like the latter, they are 

 much extended axially. The diapophyses are similarly extended axially ; and the centra 

 are similarly antero-posteriorly grooved. The twenty-first vertebra may be slightly 

 ankylosed ventrally to the twentieth. 



THE LUMBAR AND LUMBO-SACRAL VERTEBR.^. 



The vertebrae from the twenty-fifth to the thirty-second inclusive compose the lumbar 

 region. They are, of course, all ankylosed into one mass, which on its ventral surface 

 may be flat, or transversely concave, so as to present an axially directed groove. Trans- 

 verse processes are present in the four or five most preaxial vertebrae, but not more 

 postaxially (?'. e. not in the lumbo-sacral vertebrae), none others being visible when the 

 pehis is viewed ventrally. Thus there comes to be a conspicuous narrow and elongated 

 fossa on each side between the ilium and acetabulum and the vertebral column. 



PELTIS OF APTERYX (l natural size). 

 Fig. 41. 



Tectral view. 



