ABDOMINAL SOFT-FINNED FISHES. 



335 



In general, this fishery is conducted by means of nets, stretched 

 across the river, and so arranged that the Salmon are caught in the 

 meshes. But sometimes, in Scotland for example, they are speared 

 with a many-pronged weapon called a leister. They are also caught 

 with a rod and line. 



The Salmon Trout (Salmo trutta), the Common 

 Trout (Salmo fario\ the Smelts (Osmerus), and the 

 Graylings (Thymellus), all belong to this important 

 family. 



FlG. 266. -THE COMMON TROUT. 



The Herrings ( Clupeadte) have no adipose fin. The 

 upper jaw is formed in the middle by the inter- 

 maxillary bones, and on the sides by the maxillary 

 bones. Their body is always scaly. 



The Common Herrings (Clupea harengus) inhabit the northern 

 seas, and arrive every year upon different parts of the coasts of 

 Europe, Asia, and America, but do not go very far south of the 

 fortieth degree of north latitude. Some naturalists have supposed 

 that all herrings periodically retire beneath the ice of the Polar Seas, 

 and set out from this common retreat in an immense column, which 

 dividing spreads along the coasts north of the parallel above named ; 

 but this distant emigration, and this northern rendezvous in the 

 Arctic regions, are far from being demonstrated, and there is reason 

 to believe that such is not the case. 



