VERTEBRAL COLUMN 371 



b. 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. 



c. The axis or second vertebra is, with the exception 



of the atlas, the smallest of the 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. 



d. The remaining cervical vertebrae. The third and 



fourth cervical vertebrae are shorter than the 

 succeeding ones, and have short thick ribs, and 

 lateral wing-hke 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 vertebrae ; well developed 

 in the hinder ones, but almost absent in the 

 middle of the region. 



The hypapophyses are well developed in the 

 hindmost half-dozen cervical vertebrae. 



The ribs are more than half the length of 

 the vertebrae in the middle of the neck, but are 

 blunt and inconspicuous in the twelfth to the four- 

 teenth vertebrae. 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. 



2. The thoracic vertebrae are five in number. The three 

 anterior ones are fused together and with the last 



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