382 



THE VERTEBRATE SKELETON. 



behind for the passage of the spinal nerve. It is drawn out 

 above into a very long neural spine (fig. 70, A, 1), whose base 

 extends back over the succeeding vertebra and bears the down- 

 wardly-directed postzygapophyses (fig. 70, A, 6). The summit 

 of the neural arch is deeply notched in front, and on each side 

 of the notch are the prezygapophyses, which look almost ver- 

 tically upwards. The transverse processes are short and blunt, 

 and are flattened below (fig. 70, A, 3) for the articulation of 

 the tubercula of the ribs. 



B 



FlG. 70. A, SECOND THORACIC, AND B, SECOND LUMBAR VERTEBRA OF A 



DOG (Cants familiaris) SEEN FROM THE RIGHT SIDE (after VON ZITTEL). 



1. neural spine. 4. 



2. centrum. 



3. transverse process bearing in 5. 



A the facet for articulation 6. 

 with the tuberculum of the 

 rib. 



facet for articulation with the 



capitulum of the rib. 

 metapophysis. 

 postzygapophysis. 



The posterior three or four thoracic vertebrae differ much 

 from the others. The centra are longer, the neural spines short 

 and not directed backwards, the articular facets for the heads 

 of the ribs are confined to the anterior end of the centrum of 

 each vertebra, not overlapping on to the preceding vertebra. 

 The transverse processes are small and irregular, and nieta- 

 pophyses and anapophyses are developed. The prezygapophyses 



