494 



MANUAL OF ZOOLOGY 



The thoracic vertebras all have elongated spines. The 

 transverse processes are short and stout ; each bears near 

 its extremity a small, smooth articular surface or tubercular 

 facet for the tubercle of a rib. On the anterior and posterior 

 borders of each vertebra is a little semi-lunar facet, the 

 capitular facet, situated at the junction of the centrum and 

 the neural arch. The two contiguous semi-lunar facets of 

 successive vertebrae form between them a cup-like concavity 

 into which the head or capitulum of a rib is received. 



€^rh 



od art 



met 



cenl 



Fie. 298. — Lepus cuniculus. A, atlas and axis, ventral aspect, od, odontoid pro- 

 cess of axis. B, lateral view of axis, art, artictilar facet for occipital condyle; 

 od, odontoid process; pt. zy, post-zygapophysis; sp. neural spine. C, thoracic 

 vertebra:, lateral view, cent, centrum; fac, facet fnr rib; met, metapophysis; 

 pr. zy, prezygapophysis; pt. zy, post-zygapophysis; rb, rib; sp, spinous process. 



In the lumbar region the spines are comparatively short, 

 and both transverse processes and bodies are devoid of 

 facets. 



The sacral vertebras are firmly ankylosed together to 

 form a single composite bone, the sacrum. The first and 

 second bear great expanded lateral plates — sacral ribs — 

 with roughened external surfaces for articulation with the 

 ilia. 



Of the caudal vertebras the more anterior resemble those 

 of the sacral region and have similar processes; but as we 

 pass backwards in the caudal region all the processes gradu- 



