ZOOLOGY. 



segmented. In all Vertebrates above the lamprey, the verte- 

 bral column grows around the notochord, which finally 



JL 



FIG. 375. 



Fia. 376. 



Fig. 374. Transverse section through the spinal cord of a calf. , anterior, , 

 posterior longitudinal fissure ; c, central canal ; d, anterior, e, posterior cornua ; /, 

 eubstantia gelatinosa ; g, anterior column of the white substance ; A, lateral, i, pos- 

 terior column ; &, transverse commissures. After Gegenbaur. 



Fig. 375. Section through the vertebral column of Ammoccetes (lamprey). Ch, no- 

 tochord; cs, cbordal sheath ; ra, spinal chord ; a, aorta; v, veins. 



Fig. 376. Section through the spinal column of a young salmon. Ch, notochorcl ; 

 cs, cnordal sheath; m, spinal chord; k, superior, k f , inferior arch (rudimentary) ; a, 

 aorta ; , veins. After Gegenbaur. 



forms the central portion of the bodies of the vertebrae, and 

 in the higher Vertebrates is wholly effaced ; the centra or 



