Sir W. Jaidine on the Common Trout. 31 



was met with. A large fish is, however, occasionally taken on 

 the north coast, which is known by the nairje of Norway trout ; 

 this may either prove the large square-tailed bull-trout of the 

 Tweed, or one of the North European species, which appear not 

 yet to have been met with in Scotland. 



5. N^ot migrator?/. SalmoFario or Common Trout. — In North- 

 ern Europe most of the lakes and rivers are inhabited by this sec- 

 tion of the salmonidae. The north of Sutherland is a county pecu- 

 liarly adapted for them, and in the ample rivers, and rugged moun- 

 tain torrents which water her valleys, and in the lakes w hich so 

 thickly stud her wild and Alpine districts, we find these fish almost 

 the peculiar inhabitants, and abounding in the greatest profusion. 

 None of these waters, I believe, have been previously visited, with 

 the view of examining their productions, — those which had been 

 visited had only been so by the sportsman, but many have never 

 been looked at except by the shepherds who tended their mas- 

 ters' flocks on their sides. In all these lochs, the most casual 

 observer is at once struck with the dissimilarity and variation 

 which exists among the fish. The guide whom the stranger has 

 engaged to conduct him to some unexplored waters, will boast 

 of the different kinds which his loch possesses, anxious to show 

 its superiority over some others ; and trout are frequently taken 

 in different little bays, separated only by some narrow promon- 

 tory, of appearances totally distinct. The causes which produce 

 this variation in the trout (S. fario) of our lakes and rivers, has 

 not yet been attended to, and the possibility of its being the con- 

 sequence of different species inhabiting them, seems not to have 

 been thought of (at least in this county), as the reason for so 

 great differences appearing in their shapes and colour. 



Situation, the quality of the rock or soil forming the bot- 

 tom of the loch or rivers, and composing the surrounding coun- 

 try, with a difference of food, will all conduce to alter consider- 

 ably the aspect and colour of the fish. The seasons have also 

 their influence, and at that time when the great business of 

 spawning is in preparation, the form of the jaws becomes length- 

 ened, and the colours of the scales become much heightened in 

 brilliancy, — the latter a change analogous to the nuptial plumage 

 in birds, while at the completion of the breeding season, another 

 change is exhibited, incident to the then thin and transparent 

 structure of the new scales. 



2d 



