376 



THE DOGFISH 



The vertebral column has the general charactei of a 

 jointed tube surrounding the spinal portion of the neural 

 canal. Lying beneath this cavity, i.e., between it and the 

 ccelome, is a longitudinal row of biconcave discs, the ver- 



n..a. 

 I 





ha. 



fv ou 



Fig. ioi. — a, Three trunk vertebrae of Scyllium from the side. 



B, a single trunk vertebra viewed from one end. 



C, three caudal vertebrae from the side. 



D, a single caudal vertebra from one end. 



c, centrum ; h. a, hremal arch ; «. a, neural arch ; ir. pr, transverse 

 process. 



(After Hasse.) 



iebral centra (Fig. loi, c ; Fig. 99, V. Cent) : they are 

 formed of cartilage, but have their anterior and posterior 

 faces strongly calcified. The biconcave intervals between 

 them (Fig. 99, a) are filled with a gelatinous matter or inter- 



