THE CEPHALIC NEUROMERES. 



op.tr 



p.n 



FIG. 66. Same from the haemal surface, showing on the left the more superficial neurones, fiber tracts, 

 nerve roots, and commissural fibers; on the right, the deeper ones. Note the great extension backward of the 

 fibers arising from the optic nerve, op. l>, and from the giant nerve cells of the optic ganglia, op. g 4 , and olfactory 

 lobes, ol. c l and ol. c 3 . 



