D. ELECTRIC ORaANS. 



A-tr 



Electric organs are present in certain Fishes, being most 

 strongly developed in certain Raj'-s (Torpedinidse, e.g., TorpedOy. 

 Hypiios) found in the Atlantic Ocean and various southern seas, 

 in ■ a South American Eel (G-jmnotus electricus) and in an African 

 Siluroid {Malopterurus electricus). Gymnotus possesses by far 

 the strongest electric power, next to it comes Malopterurus, 

 and then Torpedo. The electric batteries of these three Fishes 



are situated in different parts of 

 the body : in the Torpedinidse they 

 have the form of a broad mass,, 

 extending throughout the substance 

 of the part of the body lying be- 

 tween the gill-sacs and the pro- 

 pterygium on either side of the 

 head (Fig. 118) ; in Gymnotus they 

 lie in the ventral region of the 

 enormously long tail (Fig. 119), 

 that is, in the position usually 

 occupied by the ventral portions of 

 the great lateral muscles ; and 

 finally, in Malopterurus, the electric 

 organ extends between the skin and 

 muscles round almost the entire 

 circumference of the body, thus 

 enclosing the Fish like a mantle:; 

 it is especially stronglj' developed 

 along the sides. 



The electric power of those 

 Fishes which were formerly known 

 as "pseudo-electric" has now been 

 fully demonstrated, though it is 

 much feebler than in the forms 

 described above. To this category 

 belong all the Rays, excluding the 

 Torpedinidse, the various species of 3Iormi/rus, and Gymnarchus- 

 (both the latter genera belonging to the Teleostei). In all these, 

 the electric organs lie on either side of the end of the tail and have 

 a metameric arrangement like that of the caudal muscles ; in the- 



Fio. 118. — Torpedo marmorata, 

 WITH THE Electric Organs {E) 



EXPOSED. 



iS, skull ; Sp, spiracle 

 Au, eye. 



KK, gills ; 



