272 SKELETON OF THE EABBIT 



the articular facets for the tubercles of the 



ribs, 

 iv. The neural spine is long and slender, and 



slopes obliquely backwards. 

 V. The zygapophyses. The pre-zygapophysep face 



upwards and outwards, the post-zygapophyses 



downwards and inwards. 



b. The posterior three or four thoracic vertebrae, 

 i. The centra are larger than in the anterior 



thoracic vertebree : the facet for the head of 



each rib is confined to the anterior end of the 



centrum, the posterior end having no articular 



surface, 

 ii. The neural spines are lower than in the anterior 



vertebrsB, but longer from before backwards, 

 iii. The transverse processes are placed further 



back, and have no articular facets for the 



ribs, 

 iv. Metapophyses appear in the ninth thoracic 



vertebra, and increase considerably in size in 



the succeeding ones. 



4. The lumbar vertebrae. 



These are usually seven in number: the most 

 anterior one may, however, bear ribs, in which case 

 it is reckoned as a thirteenth thoracic vertebra, and 

 the lumbar vertebrse become reduced to six. 



The characters of a typical lumbar vertebra have 

 already been described : as a group they are charac- 

 terised by their large size, and the great development 

 of their processes, especially the transverse pro- 

 cesses. They increase in size from before backwards, 

 the last but one being the largest. The first two 

 have hypapophyses : the last one has a short stout 

 centrum, and a stout crest-like neural spine. 



5. The sacral vertebrae. 



Strictly speaking, the sacral vertebrae are those 

 of which the expanded ribs directly support the 



