VERTEBRAL COLUMN. 297 



lamellae, consisting of the V-shaped cervical 

 ribs, the space between the articulation of 

 the rib forming the longitudinal vertebrar- 

 terial canals. In front of each transverse 

 process the canal is continued .upwards as a 

 groove to a foramen in the neural arch, through 

 which the vertebral artery enters the neural 

 canal and the first spinal nerve leaves it. 



Along the inner and hinder border of each 

 transverse process is a deep groove, corre- 

 sponding to an intervertebral notch, for the 

 passage of the second spinal nerve. 



v. The articular surfaces. The anterior end of the 

 atlas has two very large deeply concave sur- 

 faces, for articulation with the condyles of 

 the skull : the posterior end has two much 

 smaller facets for the second vertebra. 



b. The second or axis vertebra. 



i. The centrum is broad and flat, and is produced 

 in front into the conical odontoid process, 

 which is probably the centrum of the atlas 

 vertebra. The suture between the odontoid 

 process and the body of the axis is easily 

 seen in young rabbits. 



ii. The neural spine forms a large vertical crest, 

 very prominent in front, and bifid behind. 



iii. The transverse processes are small backwardly 

 directed spines, perforated at their bases by 

 the vertebrarterial canals or rib spaces. 



iv. The anterior articular surfaces are large and 

 convex, and situated at the sides of the ante- 

 rior end of the centrum. 



v. The post-zygapophyses project backwards from 

 the hinder edge of the neural arch, their 

 articular surfaces facing downwards and out- 

 wards. 



