318 A COURSE ON ZOOLOGY. 



that are found in the same waters. The muskallunge 

 of the St. Lawrence and of the large northern lakes is 

 a fish of the same family ; it 

 FIG. 275. attains a very large size. 



Herring have been supposed 

 to migrate annually, and their 

 appearance in certain parts is 

 so uniform that the direction of 

 their voyages was considered 

 TEETH OP THE PIKE (camiv- known ; starting from the North- 

 ern Atlantic, they appear to 



form two immense shoals, one of which takes a westerly 

 direction towards America, while the other descends 

 towards the European seas and breaks up into three 

 divisions ; one of these proceeds towards the British 

 Isles, another towards Norway and the Baltic, and 

 the third enters the North Sea, crosses the English 

 Channel, and advances as far as the mouth of the 

 Loire. Eecent investigations, however, seem to show 

 that the migration is only apparent, and that during the 

 greater part of the year the herring live at considerable 

 depths in the ocean where the nets cannot reach them ; 

 at the beginning of the spawning season they ascend 

 all at once, and appear from place to place on the coast ; 

 thus, there is no travelling from north to south, but a 

 change from deep to superficial water. The herrings 

 place their eggs in a froth which they blow up on the 

 surface of the water. 



Sardines are taken principally in the Mediterranean 

 and on the coasts of Brittany ; more than six hundred 

 million are caught every year, and as soon as caught 

 they are salted, for they spoil very quickly. Some are 

 sent to market in salt, the rest are preserved in oil. 



