VERTEBRAL COLUMN. 405 



their articular surfaces facing downwards and 

 outwards. 



The atlas, or first vertebra, is very short and ring- 

 like. Its ventral portion is thickened, resembling 

 a centrum, and is notched above to receive the 

 odontoid process of the axis : its anterior surface 

 is deeply cupped to articulate with the occipital 

 condyle of the skull. The posterior border of 

 the neural arch is produced backwards into zyg- 

 apophyses, articulating with the second vertebra. 



The axis or second vertebra is, with the exception 

 of the atlas, the smallest of the cervical series : 

 it has a blunt neural spine, but no transverse 

 processes, and no ribs. The centrum is produced 

 in front into the slender odontoid process. 



The remaining cervical vertebrse. The third and 

 fourth cervical vertebrse are shorter than the 

 succeeding ones, and have short thick ribs, and 

 lateral wing-like ridges placed obliquely along 

 their sides. The middle cervicals are the longest 

 of the series, and the hinder ones are shorter 

 and more massive. The last cervical vertebra is 

 fused with the first thoracic. 



The neural spines are present, though small, 

 in the anterior cervical vertebrse : they are well 

 developed in the hinder ones, but are almost 

 absent in the middle ones of the region. 



The hypapophyses are well developed in the 

 hindmost half-dozen cervical vertebrse. 



The ribs are more than half the length of 

 the vertebrse in the middle of the neck, but are 

 blunt and inconspicuous in the twelfth to the 

 fourteenth vertebrse. In the fifteenth the ribs are 

 well developed, and movably articulated with 

 the vertebra ; and in the sixteenth they are still 

 larger, and resemble the thoracic ribs, but do not 

 meet the sternum. 



