374 



ZOOLOGY. 



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

 bral column grows around the notochord, which finally 



Fia. 371. 



Fig. 369. Transverse section through the spinal cord of a calf, a, atiterior, ft, 

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

 Bubstautia gi'latinosa; g, anterior column of the white substance; h, lateral, i, pos- 

 terior column ; A 1 , transverse commissures. After Gegenbaur. 



Fig. 370. Section through the vertebral column of Ammocoetes (lamprej-)- Ch, no- 

 tochord; ex, chordal sheath ; m, spinal chord ; , aorta; v, veins. 



Fie 371. Section through the spinal column of a young salmon. Ch, notochord ;. 

 cs, chordal sheath; m, spinal chord; k, superior, k', inferior arch (rudimentary) ; a, 

 aorta ; v, veins. After Gegenbaur. 



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

 in the higher Vertebrates is wholly effaced ; the centra or 



