AVES. 



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(b) Vertebral Column and Ribs. The vertebral column is 

 divided into regions, arranged as follows : 



The cervical vertebrae are those supporting the neck. Each is 

 made up of two parts : (a) An elongated centrum, articulating 

 with neighbouring centra by saddle-shaped surfaces conferring 

 great flexibility to this region, and with a median ventral process 

 (hypapopliysis). (b) A neural arch, produced dorsally into a plate- 

 like neural spine, and connected with adjacent arches by pre- and 

 post-zygapophyses in the same way as in the frog. Intervertebral 

 foramina are left between the arches for the transmission of the 

 spinal nerves. 



The last cervical vertebra possesses a strong transverse pi'ocess 

 running out from each side of the neural arch, and bears a pair 

 of cervical ribs, each of which is a small curved bone, with a 

 forked proximal end attached to the vertebra, and a free distal 

 end. From its hinder edge a small flat uncinate process projects. 

 The two limbs of the forked end terminate in articular projections 

 termed head (capitulum) and tubercle. The former articulates 

 with a small capitular facet on each side of the centrum near its 

 front end, the latter with a similar tubercular facet on the under 

 side of the transverse process. The last vertebra but one also 

 bears free ribs, these, however, are devoid of tubercles and 

 uncinate processes. 



In the remaining vertebrae which possess them, the cervical ribs 

 are very short, and completely fused with the transverse process 

 and centrum, an aperture being left, however, which, with those 



