569 



s.o.. 



O.P. 



V. 



Fig. 1. Horizontal section through mid brain of Torpedo ocellata. 

 O.P. ophth. profundus, S.O. primitive branchial sense organ, r. Trige- 

 minus. 



Fig, 2, Similar section later stage. T. ocellata. M.O. Third nerve. 

 S.O. primitive branchial sense organ. M.G. mesocephalic ganglion. G.G. 

 Gasserian ganglion. H.C.I, first Head Cavity, h.y. hyoid arch. M.B. Mid 

 brain. 



