142 



ANATOMY OF THE CENTRAL NBBTOUS SYSTEM. 



in the optic nerve after loss of the eyes could be compared with the Tisual 

 images received during life. 



The decussation is not, however, so simple as represented in Figs. 87 

 and 89. The bundles are plaited together more or less, in fishes one nerve . 

 passing through a slit in the other. 



Tela chorioid. 

 Tr. striO'thalam. 



Tr. opticus 



Dec\is. Tr. tegmento-cereboU. 

 * Dee. hypoth. sup. 

 .* Genieul. lat. 

 .. N. oculo-mofc. 

 , Tr. tecto-bulb. et spin. 



— Comm. ansul. 



Fig. 92. — Horizontal section through the brain of the ScylUum canioula to show 

 the decussations in the base of the brain. 



Beyond the chiasma the reunited fasciculi pass backward and up- 

 ward (Fig. 88), inclose the thalamus, sending into the externally located 

 Corpus geniculatum a large portion of the collaterals from the fibers (com- 



