424 ME. ST. GEOEGE MIVAET ON THE 



with each lateral margin extremely concave, through the two parapophysial processes 

 which the centrum throws out. The preaxial one of these is the more considerable. 

 The neural foramen of the centrum is again rather larger. 



The Thiktt-poueth Vektebea. 



This vertebra (figs. 59, 60, & 61, e) has again its neural arch supported on two 

 centra ; but it rests rather more on its own. It has a larger dorsal defect of ossification 

 (fig. 61, o) than in the thirty-thii'd vertebra, extending quite from the diapophysis to 

 the neural spine. 



The neural spine is slightly less extended, though still anchylosed both pre- and post- 

 axially, even in the young. 



Its dia])0]}hysis is rather longer (fig. 61, d^) than in the last vertebra, and inclined 

 more preaxiad. Both the pre- and postaxial intervertebral openings are smaller. 



Its centrum, the ventral siurface of which is exceedingly short antero-posteriorly, forms 

 half of a large parapophysial surface (fig. 60, p^) at its preaxial part, and the greater 

 part of a very much smaller j)arapophysial surface at its postaxial part. 



The neural foramen of the centrum is again large ; it is here almost at its maximum 

 (fig. 61, 6). 



The Thikty-pipth Veetebka. 



This vertebra (figs. 59, 60, & 61, 7) rests mainly on its own centrum. The postaxial 

 intervertebral opening is bounded below by its neiiral arch. The defect of ossification 

 of this neural arch is at its maximum (fig. 61, 7), and more dorso-ventrally extended 

 than in the thirty-foiu'th vertebra. 



The diapop/ii/sis is longer, almost as slender as in the last vertebra, and inclined more 

 preaxially (fig. 61, 7). 



The parapophysial surface is much smaller, and is formed less by its own centrum 

 than by that of the more preaxial vertebra. 



The postvertebral interspace is again rather smaller. 



The neural foramen of the centrum is smaller. 



THE SACRAL VERTEBRA. 



The Thiety-sixth Vertebea. 



This vertebra (figs. 59, 60, & 61, 8) is distinguishable in the adult as that which fur- 

 nishes (from the preaxial end of its centrum) the first of those three parapophysial roots 

 which ascend and meet together to form the large bony plate which abuts against the 

 ilium just behind the acetabulum. 



In the young it is easily distinguishable as the most preaxial one which develops from 

 the preaxial end of its centrum a sutui'e-united parapophysial process or capitulum of 

 a rib (fig. 60, /). 



