252 FISHES. 



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. 



FIG. 266. THE COMMON TROUT. 



The Herrings (Clupeada] have no adipose fin. The upper jaw 

 is formed in the middle by the intermaxillary bones, and on the 

 sides by the maxillary bones. Their body is always scaly. 



The Common Herring's (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 they merely recede from the shore. 



In the months of April and May herrings begin to appear off the Shetland Islands, 

 and towards the end of June, or in July, they arrive in incalculable numbers, forming 

 vast and dense shoals, which sometimes extend over the surface of the sea for several 

 leagues, and are hundreds of feet in thickness. The herring-fishery is of great import- 

 ance; it occupies every year entire fleets, and formerly was carried on with still greater 

 activity. About the middle of the seventeenth century, the Dutch employed not less 

 than 2,000 vessels ; and it is estimated that 800,000 persons in Holland and West Fries- 

 land derived their living from this branch of industry alone. 



Herrings are generally caught by means of nets, five or six hundred fathoms in 

 length, the lower edge of which is loaded with lead, while the upper edge is made to 



