158 THE STORY OF FISH LIFE. 



year only, especially the season of propagation, 

 as the barbel, pike and burbot, whose roe causes 

 violent diarrhoeas when eaten during the season 

 of spawning." 



It is probable, however, that the presence of 

 poison in the cases just related is an accidental 

 character, and such fishes are, therefore, to be 

 distinguished from those which secrete poison at 

 certain restricted areas of the body and in con- 

 nection with spines, for the purpose of causing 

 punctures for the admission of the venom. 



More remarkable than the poisonous are the 

 electrical properties of fishes. No less than fifty 

 species of electrical fishes are known to science, 

 though only a few, some five or six, species have 

 been carefully studied. These are Gymnotus, the 

 electric eel of the rivers and lagoons of Brazil 

 and the Guianas ; Malapterurus, the raash or 

 thunderer fish of the Arabs, found in the Nile, 

 Niger, and other African rivers ; the torpedo or 

 electric skate of the Mediterranean and Adriatic, 

 and various species of British skates. 



It will be noticed from the above list that the 

 electrical fishes are by no means always closely 

 related, neither are they confined either to fresh 

 or salt water. 



The electrical powers are most strongly de- 

 veloped in gymnotus, the South American eel; 

 next in order of strength comes the malapterurus ; 

 then the torpedo. The electric organs, or bat- 

 teries, are seated in different parts of the body in 

 these three fish. In the torpedo they form a 

 broad mass lying on either side of the head, and 

 extending backwards on either side to terminate 



