374 



ZOOLOGY. 



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

 bral column grows around the notochord, which finally 



Fio. 371. 



Fig. 369.— Tranaveree section tlirough the spinal cord of a calf, o, anterior, 6, 

 poeterior longitudinal fissnre ; c, central canal ; rf, anterior, e, posterior cornua ; /, 

 substantia gelatinosa ; g, anterior column of the white eubetaiice ; A, lateral, i, pos- 

 terior column ; It, transverse commissures. —After Gegenbaur. 



Fig. 370.— Section through the vertebral column of Ammoccetes Gamprey). C%, no- 

 tochord; c«, chordal sheath ; m, spinal chord ; a, aorta; », veins. 



Fig. 371,— Section through the spinal column of a young salmon. C%, notochord ; 

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

 aorta ; i), veins.— After Gegenbaur. 



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

 in the higher Vertebrates is wholly effaced ; the centra or 



