ELECTRIC ORGANS. 217 



proper sympathetic nerve, this being replaced by the vagus. It has 

 been found in the Myxinoidae that the vagus nerve is not limited to 

 supplying branches to the stomach, but that upon the cardiac extrem- 

 ity of the latter viscus a single intestinal branch arises from both 

 vagi, and passes along the whole length of the intestinal canal to the 

 anus, and gives off those nerves of the organic system that are in 

 other Fishes furnished by the sympathetic. The lateral nerve is 

 present in Petroinyzon, but is so short that it supplies with branches 

 only the anterior third of the body. 



ELECTRIC ORGANS. 



IT is in the class of Fishes (and according to what has been hith- 

 erto observed, in this class of animals alone) that we meet with cer- 

 tain species which are provided with remarkable apparatus, capable 

 of producing, like an electrical machine or galvanic pile, electric 

 shocks, and so constituting weapons whereby these animals both 

 defend themselves and entrap their prey. 



These Electrical Fishes, as they have been called, are some in- 

 habitants of the sea, others of fresh water ; and all the species 

 known at present belong to the order Plagiostomi and to the soft- 

 finned Fishes. All the known electrical Fishes are characterized by 

 a smooth, naked, or scaleless integument provided with numerous 

 mucous canals. Two genera are known to belong to the family of 

 Rays. The European Electric Rays form the genus Torpedo, and 

 comprise two species, the T. narke s. ocellata and T. Galvanii s. 

 marmorata ; to these may be probably added a third, described by 

 L. Bonaparte under the title of T. nobiliana, and which is of very 

 rare occurrence. The first two species exist chiefly in the Mediter- 

 ranean and Adriatic seas, are in rare instances found in the Atlantic 

 ocean, and occasionally roam as far as the English coast and the 

 Northern sea. A peculiar species discovered by Ehrenberg^and 

 Hemprich, the T. Panthera, has been found also in the Red sea. 

 A second genus, Narcine, very similar to Torpedo, is found upon the 

 coasts of Brazil and India; three species of it are known. 



From the family of Eels we are already acquainted with the 

 Gymnotus electricus, that has been brought alive to Europe, and is 

 met with in the inland seas and small tardily-flowing rivers of 

 southern tropical America, especially in Colombia, Surinam, and 

 Guiana. 



The third electrical Fish, Silurus electricus, belongs to the family 



