PLATE V. 



Fig. 1. The axis, or vertebra dentata, front view. 



Fig. 2. The axis, or vertebra dentata, side view. 



Fig. 3. The third cervical vertebra, front view. 



Fig. 4. The third cervical vertebra, side view. 



Fig. 5. The sixth cervical vertebra, front view. 



Fig. 6. The sixth cervical vertebra, side view. 



One-fourth natural size; o, odontoid process (centrum of atlas) ; zn, ana- 

 logues of anterior zygapophyses, in the dentata ; z, anterior zygapo- 

 physis ; z', posterior zygapophysis ; d, diapophysis ; p, parapophysis ; pi, 

 pleurapophysis, pi, its anterior production; m, metapophysis ; ns, neural 

 spine. 



