TRANSFORMATIONS. 1 59 



at the level, and to the outer side of the hindmost 

 gill-slit. In the gymnotus they lie in the ventral 

 region of the tail, which is enormously elongated, 

 displacing the ventral postures of the powerful 

 lateral muscles. In the malapterurus the electric 

 organ invests the body like a mantle, lying be- 

 tween the skin and the muscles of the body. 



In the British species of -skate, various species 

 of Mormyrus and Gymnarchus (African beaked-fish), 

 the electric organs lie on either side of the end 

 of the tail. These fishes were formerly described 

 as pseudo-electric, the shock which they give 

 being comparatively feeble. Recently, however, 

 the possession of an electric organ has been fully 

 demonstrated, lying, as we have indicated, in the 

 tail. 



The electrical organ is to be regarded as 

 modified muscle-tissue. Dr Giinther has thus 

 graphically described those of the torpedo. 

 " The electric organs with which these fishes are 

 armed are large, flat, uniform bodies, lying one 

 on each side of the head, bounded behind by the 

 scapular arch, and laterally by the anterior cres- 

 centric tips of the pectoral fins. They consist of 

 an assemblage of vertical hexagonal prisms, whose 

 ends are in contact with the integuments above 

 and below ; each prism is sub-divided by delicate 

 transverse septa, forming cells, filled with a clear, 

 trembling jelly-like fluid, and lined within by an 

 epithelium of nucleated corpuscles. Between 

 this epithelium and the transverse septa and 

 walls of the prism there is a layer of tissue in 

 which the terminations of the nerves and vessels 

 ramify. Hunter counted 470 prisms in each 



