MACKREL. 507 



grows to a larger size than elsewhere, and is supposed to find its 

 favourite food, consisting chiefly of marine insects, in far greater 

 plenty than in warmer latitudes. During the severity of the northern 

 winter, it is said to lie imbedded in the soft mud, beneath the vast 

 crusts of ice surrounding the polar coasts; being thus sufficiently 

 protected from the etfects of frost ; and, on the return of spring, is 

 generally believed to migrate in enormous shoals, of many miles in 

 length and breadth, and to visit the coasts of more temperate cli- 

 mates in order to deposit its spawn. Its route has been supposed 

 nearly similar to that of the herring ; passing between Iceland and 

 Norway, and proceeding towards the northern part of our own 

 island, where a part throws itself off into the Baltic, while the grand 

 column passes downwards, and enters the Mediterranean through 

 the straits of Gibraltar. 



This long migration of the mackrel, as well as of the herring, 

 seems at present to be greatly called in question : and it is thought 

 more probable that the shoals which appear in such abundance 

 round the more temperate European coasts, in reality reside during 

 the winter at no very great distance ; immersing themselves in the 

 soft bottom, and remaining in a state of torpidity * ; from which 

 they are awakened by the warmth of the returning spring, and 

 gradually recover their former activity. At their first appearance 

 their eyes are observed to appear remarkably dim, as if covered 

 with a kind of film, which passes off as the season advances, when 

 they appear in their full perfection of colour and vigour. 



The general length of the mackrel is from twelve to fifteen or 

 sixteen inches ; but in the northern seas it is occasionally found of 

 far greater size, and among those which visit our own coasts in- 

 stances sometimes occur of specimens far exceeding the general 

 size of the rest. The colour of this fish, on the upper parts, as far 

 as the lateral line, is a rich deep blue, accompanied by a varying 

 tinge of green, and marked by numerous black transverse streaks, 

 which in the male are nearly straight, but in the female beautifully 

 undulated ; the jaws, gill-covers, and abdomen, are of a bright 



* Of this the Count de Cepede adduces the testimony of an eye-witness ; 

 viz. Mons. Pleville-le-Peley, who, about the coasts of Hudson's Bay, ob- 

 served the mud, at the bottom of the small clear hollows encrusted with ice 

 round those coasts, entirely bristled over by the tails of mackrels imbedded in 

 it nearly three parts of their length. 



