386 ZOOLOGY. 



Finally, the silurus electricus or malapterarus (Fig. 397), is 

 a native of the Nile and the Senegal : its length varies from 

 a foot to fifteen inches, and its electric properties seem to 

 reside in a particular space, situated between the skin of the 

 flanks and the muscles, resembling a leafed cellular tissue. 

 The Arabs call it the raasch, which signifies thunder. 



490. Fishes multiply by means of eggs, and a single 

 spawning in some produces hundreds of thousands. In 

 general they have only a mucilaginous protecting envelope, 

 and they are hatched after spawning without any care on the 

 part of the parent. But some are ovoviviparous. However this 

 may be, they are all abandoned by their parents, and many 

 perish. It is probably owing to the circumstances connected 

 with the birth, that fishes are found in vast troops, called by 

 the fishermen banes. These reunions can scarcely be called 

 societies, and they probably follow each other from a tendency 

 to imitation. 



Fig. 397. Electric Malapterurus of Africa. 



491. However this may be, these animals unite in vast 

 troops to ascend rivers or to change their habitat. Some 

 lead a sedentary life, remaining always in the same locality ; 

 others are constantly wandering, and some perform distant 

 voyages. At fixed periods of the year they assemble in vast 

 numbers from regions which, if not distant, are at least un- 

 known. This is the case with the herring, and the same may 

 be said of the salmon. The herrings deposit their eggs near 

 the coast, and the young retire, in all probability, merely into 

 deeper waters. The idea of their travelling to and from the 

 Arctic Seas seems quite a fable. They appear on the coast in 

 winter and in early spring, and again at midsummer and 

 during the autumn. Their numbers when they first appear 

 seem incredible ; but they are capricious, and will abandon 



organs ; np, pneumogastric nerves proceeding to the electric organs ; nl, a 

 branch of the preceding forming the lateral nerve; n, spinal nerves. 



