AXIAL SKELETON OF THE OSTRICH. 



425 



Compared with the thirty-fifth vertebra, its neural arch is more antero-posteriorly 

 extended, and shows a less defect of ossification dorsaUy (fig. 61, s). Ventrally the 

 neural lamina extends postaxially over the preaxial half of the root of the capitulum of 

 the next vertebra, and thence ascends so as completely to enclose the postvertebral per- 

 foration, so that the neural arch may be said to be rather perforated than postaxially 

 notched. The postvertebral interspace or perforation is considerably larger than in the 

 three preceding instances. 



The diapoiJhysis (figs. 59, 60, & 61, <Z*) is remote from the parapophysis, is stouter 

 than that of the preceding vertebra, and extends more outwards and less preaxially. 



The parapoi}hysis is a scarcely noticeable prominence from the side of the preaxial 

 part of the ventral side of the centrum ; and this concurs with a process from the post- 

 axial part of the thirty-fifth' vertebra (fig. 60, 7&8) to form a sm-face for the capi- 

 tulum. This capitulum arises thence by an expanded base with a somewhat hexagonal 

 outime, rapidly contracts, then rapidly expands, ascending dorsally and postaxially to 

 ancbylose with the similar expansion of the capitulum next behind, and contributing to 

 form the dorsally and postaxially extended surface (fig. 59,jj*"°) which abuts against 

 the postacetabular part of the ilium. 



The Thirty-seventh Vertebra. 



This vertebra (figs. 59, 60, & 61, o) has a lower neural spine, which, in the young, is 

 free both pre- and postaxially. 



Its centrum, but not its neural arch, is more extended antero-posteriorly than in the 

 last vertebra. 



DORSAL ASPECT OF LUMBAR AND SACRAL VERTEBRA OP AN IMMATURE SPECIMEN 



(I natural size). 



Fig. 61 . 



i>.8.9Jx)' I dm 



da 



1-12. Neural arches of vertebrfe from the twenty-ninth to the fortieth inclusive ; cP-d^", diapophyses of these 

 vertebrEE to the thirty-eighth inclusive ; d^}", conjoined di- and parapophysis of the thirty-ninth vertebra ; 

 p*'"", conjoined oapitiila of sacral vertebrae; s\ neural spine of twenty-ninth vertebra. In the neural 

 arches of the vertebrae from the thirty-third to the thirty-sixth, considerable defects of ossification are to 

 be seen. 



VOL. VIII. — PART VII. March, 1S74:. 3o 



