262 



PISCES. 



before the pectorals; the anus very far forwards; anal fin occupying 

 the greater part of the inferior surface of the body, and most fre- 

 quently extending to the end of the tail; no dorsal fin whatever. 



Gymnotus, Lacep. 



No fin at the end of the tail, under which extends the anal. 

 The True Gymnoti have no sensible scales; their intestines which 

 have several flexures occupy but a moderate space; the caeca are nu- 

 merous, and the stomach resembles a short obtuse sac strongly 

 plaited within. One of their air vessels, cylindrical and elongated, 

 extends very far behind in a sinus of the abdominal cavity, the 

 other, oval and bilobate, composed of a thick substance, occupies 

 the upper part of the abdomen, and is placed on the CEsophagus. 

 The species known inhabit the rivers of South America. The most 

 highly celebrated is 



G. ehctricus, L.; BL, 156 (The Electrical Gymnotus); 

 which, from its almost uniform shape and obtuse head and tail, 

 has also been called the Electrical Eel. It is from five to six 

 feet long, and communicates such violent shocks that men and 

 horses are struck down by them. This power is dependent on 

 the will of the animal, which gives it what direction it pleases, 

 and renders it effective, even at a distance, killing fishes there- 

 with, so situated. It is, however, dissipated by use, and to renew 

 it, the Gymnotus requires rest and nourishing food.(l) The or- 

 gan which is the seat of this singular faculty, extends along the 

 whole under side of the tail, occupying about half its thickness; 

 it is divided into four longitudinal fasciculi, two large ones 

 above, and two smaller ones below, and against the base of the 

 anal fin. Each bundle is composed of numerous parallel, mem- 

 branous laminae, nearly horizontal, and closely approximated 

 to each other, one end terminating on the skin, and the other on 

 the median vertical plane of the animal; they are united with each 

 other by a multiplicity of small transverse and vertical laminae. 

 The little cells, or rather the little prismatic and transverse 

 canals formed by these two kinds of laminae, are filled with a 

 gelatinous matter, and the whole apparatus receives a propor- 

 tionably large number of nerves. (2) 



(1) See Humboldt, Zool. Obs. , I, p. 49, at seq. 



(2) See Hunter, Phil. Trans, vol. LXV, p. 395. Add the Gymnotus xquita- 

 biatus, Humb., Zool. Obs., I, pi. x, No. 2, according to whose observations this 

 .species has no posterior natatory bladder. 



