THE SKELETON OF THE DOG. VERTEBRAL COLUMN. 379 



from the centre of the dorsal surface is a prominent median 

 neural spine or spinous process, which projects upwards 

 and slightly forwards ; its anterior edge is vertical, while its 

 posterior edge slopes gradually. At the two ends of the 

 neural arch arise the two pairs of zygapophyses or articula- 

 ting surfaces, which interlock with those of the adjacent 

 vertebrae. The anterior or prezygapophyses look inwards, 

 and are large and concave ; they are borne upon a pair of 

 large blunt outgrowths of the neural arch, the metapophyses. 

 The posterior or postzygapophyses are slightly convex and 

 look outwards and downwards ; they are borne upon back- 

 warclly projecting outgrowths of the neural arch. Lastly 

 there are a pair of minute projections arising from the 

 posterior end of the neural arch, below the postzygapophyses. 

 These are the anapophyses. In young individuals the de- 

 velopment of all the processes of the various vertebrae is less 

 marked, arid the epiphyses are obviously distinct. 



FlG. 69. A, ATLAS AND B, AXIS VERTEBRA OF A DOG (CaillS 



familiaris) (after VON ZITTEL). 



1. transverse process of atlas. 



2. vertebrarterial canal. 



3. foramen for exit of spinal 



nerve. 



4. neural spine. 



5. odontoid process. 



6. anterior articulating surface 



of centrum. 



7. centrum. 



8. transverse process of axis. 



9. postzygapophysis. 



