OSTARIOPHYSI 5 9 I 



in numerous bands, baskets of the small Fish being filled by 

 the Indians who' come across them.-' The African Synodontis 

 are much in the habit of floating or swimming leisurely on the 

 sm'face with the belly in the air, as was well known to the 

 ancient Egyptians, who have frequently depicted the Fish in 

 this anomalous position. A curious fact in connexion with 

 this habit is that S. memiranaceus and S. batensoda, in which 

 it has most frequently been observed, show an inversion of the 

 ordinary mode of coloration, the lower parts being dark brown 



Fig. 357. — Synodontis decerns, from the Congo. J nat. size. 



or black and the upper pale silvery grey. The electric Cat-Fish 

 (Mcdoptertirus electriciis), is also a native of Africa, occurring all 

 over the tropical parts of that continent and also in the Lower 

 NUe, growing to a length of three feet. Its flesh is more 

 esteemed than that of other Silurids. It avoids light and is slow 

 in its movements. The electrical apparatus differs absolutely 

 from that of all other Fishes, being derived from the integument, 

 belonging to the glandular system, and surrounding the whole 

 body with a thick coat of grease or gelatinous substance ; the 

 apparatus is governed by a single nerve on each side proceeding 

 from a huge ganglionic cell at the anterior extremity of the spinal 

 cord.^ The shocks given by Mcdopterurus are very powerful, and 

 the Fish is called " Raad " by the Arabs, a name which means 

 " thunder." Kept in an aquarium with other Fishes, even of the 

 same species, the " Eaad " soon kills its companions. 



^ Cf. Hancock, Zool. Journ. iv. 1829, p. 242. 



^ Cf. G. Fritsch, "Die Elektrischen Fisohe, I. Malopierurus " (Leipzig, 1887) ; E. 

 Ballowitz, "Das elektrische Organ des Afrikanischen Zitterwelses " (Jena, 1899). 



