46 M. du Bois-Reymond on the Electrical Silure. 



in Western Africa, on the Old Calabar river, which discharges 

 itself into the Bay of Benin in latitude 51° N.,and longitude 8° W. 

 The fish was described by Mr. Andrew Murray of Edinburgh 

 as a new species under the name of Malapterwus Beninensis*. 

 A lady, the wife of a missionary, notwithstanding her having 

 been shipwrecked, has now succeeded in bringing three living 

 specimens of the same species to Edinburgh. Professor Goodsir 

 of Edinburgh, who is now travelling through Germany, has had 

 the extraordinary kindness to bring one of these three fishes to 

 Berlin and to place it at the disposal of Prof. J. Mliller, who 

 has handed it over to me for experiment. 



The fish was the smallest, but the most lively of the three ; it 

 measures about 15 centimetres (6 inches) in length. It travelled 

 here by Leith and Rotterdam, with a few aquatic plants in an 

 ordinary gold-fish globe, which was placed in a suitable covered 

 basket. Since Saturday last it has been kept at the Anatomical 

 Museum in a larger vessel with aquatic plants and water from 

 the Spree, and appears to be very comfortable. It seeks the 

 dark, and is very quiet. They have not succeeded with certainty 

 in feeding it. The spirit-specimens examined in Edinburgh had 

 the remains of freshwater Crustacea in their intestines ; and the 

 living fishes immediately chased similar pelagic forms which 

 were oflFered to them, and appeared, although they allowed them 

 to escape again at first, to have finally eaten them. Accordingly, 

 we are endeavouring to feed our Silure with the small Crustacea 

 of this country, such as Gammarus, Asellus, Daphnia, &c. 



For the present it appears advisable to call forth the electrical 

 power of the fish as little as possible. I have therefore hitherto 

 confined myself to the examination of the most important point 

 now feasible, namely to ascertain the distribution of the electric 

 tensions, which is still unknown. 



According to the concurrent statements of many observers, at 

 the moment of the shock in the Torpedo, the dorsal surface of the 

 organ is positive, and the ventral surface negative; that is to 

 say, the current passes in the organ from the belly to the back, 

 and in the surrounding water, or a curved conductor applied to 

 the two surfaces, from the back to the belly f. 



Of the Malapterurus of the Nile, we have recently had a de- 

 scription elaborated with all the modern aids, by M. Bilharz, a 

 German naturalist living in Cairo %, so that in a morphological 



* Edinburgh New Philosophical Journal, New Scries, vol. ii.pp. 49, 379; 

 and vol. iii. p. 188. British Association Report, 1855, p. 1 14. 



t Experimental Researches in Electricity, Scr. XV. Nov. 1838. Nos. 1761, 

 1764. 



X Das electrische Organ des Zitterwelses anatomisch beschrieben, &c. 

 Leipzig, 1857, folio. 



