THE ELECTRICAL ORGANS. 



55 



upper and under surHices of the body ; posterior in Gymno- 

 tus, and anterior in JIalapterurus, the lamellae being disposed 

 perpendicularly to the axis in these two fishes. And this sur- 

 face, when the discharge takes place, is always negative to 

 the other. 





ii f.l»'.^r,',^^,r-:_^ », 









Fig, 18.— The Torpedo, with its electrical apparatus displayed. — &, branchia>; c, brain; e, 

 electric organ ; ^, cranium; 7ne, spinal cord; «, nerves to the pectoral lins ; nl, nervl 

 later ales ; np, branches of the pneumogasti-ic nei-ves going to the electric organ ; o, 

 eye. 



Ill Torpedo the nerves of the electrical organs proceed 

 from the fifth pair, and from the " electric lobe " of the 

 medulla oblongata^ which appears to be developed at the 

 origin of the pneumogastrics. In the other electrical fishes 

 the organs are supplied by spinal nerves ; and, in Mala/pter 

 ruTUS, the nerve consists of a single gigantic primitive fibre, 

 which subdivides in the electrical organ. 



The ordinary Rays possess organs of much the same 

 structure as the electrical apparatus, at the sides of the tail. 



The JVervoiis System: the JEJncejjhalon. -^In. all vcrte- 

 brated animals except A.m2:)hioxus, the brain exhibits that 

 separation into & J'ore-brain,7nid-brain, and hlnd-hraiyi^ which 



