54 



FISH GALLERY. 



The series of bones constituting the axis of the body, and des- 

 tined to protect the spinal cord and some large longitudinal 

 blood-vessels, is called the vertebral or spinal column ; the single 

 bones are the vertebra. 



The vertebra consists of a body or centrum (fig. 41, c), with a 

 concave anterior and posterior surface, and of several processes or 



Vertebra of Fish. 



apophyses, as : — 1. Two neurapophyses (na) which, on the dorsal 

 side, rising upwards, form the neural arch over the canal, in which 

 the spinal cord is lodged. 2. Two parapophyses (jpa), projecting 

 from the lower part of the sides of the body, or two hamapophyses 

 (ha), which coalesce to form on the ventral side the haemal canal 

 for a large trunk of the vascular system. 3. A neural spine (ns\ 

 which crowns the neurapophyses. 4. A heemal spine (hs), having 

 the same relation to the hsemapophyses. 5. Two pleur apophyses 

 or floating ribs, suspended from the parapophyses. 6. Oblique 

 articular processes, zygapophyses (za), developed from the base of 

 each neurapophysis. 



The vertebrae are divided into abdominal and caudal, the latter 

 distinguished by the coalescence of the parapophyses into a com- 

 plete haemal ring; the suspension of the anal fins forms the boundary 

 between the two divisions (fig. 37). The abdominal vertebra?, 



