31 VERTEBRAL OOLUMX 499 



anteriorly into a conical odontoid process, which fits into the 

 lower part of the ring of the atlas and is held in its place by 

 a ligament extending transversely across the latter : it is 

 ossified from a distinct centre, which really belongs to the 

 centrum of the atlas. The neural spine of the axis is eJon- 

 ;.i:e-i ~:.-- ':. : :~7Te:.->e- : . i~i ::.5 :r.i"^ vr^-v v: .-;?.?.-? ~~; :-,.'. 

 and perforated each, by a vertebrarterial canal ; zygapo- 

 physes are present only on the posterior face of the arch. 

 In 'an the other cervical vertebrae, the transverse processes 



.ITr .-...>: 7'rT: r.-."r'l . V Vr . . r 7 3.. .f . ~L- M7..1. f 1" .". rX.'rT" IT. 



the seventh or last, are divided into dorsal and ventral 

 lamella*. The zygapophyses resemble those of the thoracic 

 vertebra described above. The seventh cervical vertebra 

 has a longer spine than the others, and bears a pair of half 

 facets on the posterior surface of its centrum with, which the 

 first pair of ribs in part articulate. 



typical tkgiracsc vertebra has already been described. 

 In the tenth, the neural spine is vertical, and in *h remain- 

 ing two or three, winch are larger than the others, it slopes 

 forwards. In the posterior three or four there are no tuber- 

 cular facets, the ribs in this region not being forked ; the 

 capitular facets are entire, and are situated on Idle conre- 

 " spending centrum only. Additional processes are present 

 above the pre-zygapophyses from the ninth thoracic 

 verier T.I ; - "' ~ ~.-*~ ~.~ 



The lumbar vertebrae are relatively large, increasing in 

 size from before backwards, and their various processes are 

 greatly developed. The neural spines are directed upwards 

 and forwards, the trars verse processes are large and pro- 

 ject outwards, downwards and forwards. As in the pos- 

 terior thoracic vertebra?, 'there are stout processes above the 

 (which face nmsuuds}, and there is also a 



pair of more slender processes below the post-zygapophyses 

 (which, face outwards), and a median ventral process pro- 

 jecting downwards from the centrum is present on the 

 Just two. 



The sacral vertebra? are fused to form the smcrtam, which 

 supports the pelvic arch. The first and to a less extent 

 the second also has large, expanded, transverse processes 

 which articulate with the ina ; these are the sacral vertebrae 

 proper ; the others, which decrease in size from before back- 

 wards, are really the anterior caudal vertebra? which fuse 

 with the true sacral vertebrae to form a amtptrnwl saantm, 



The more anterior caudal vertebra? resemble those of the 

 sacral region, but on passing backwards an the processes are 

 seen to diminish in a\ until only the centra, are left at the 

 ezi :: 



