VARIETIES OF COLOUR. 115 



of the head and gill-covers, the form of the fins and the nnmber 

 of the fin-rays, things not examined by the superficial observer, 

 they would pass for different fish. These three varieties are 

 known as the Truite de Greve, Truite des Battures, and Truite 

 du Large ; or, Trout of the muddy bottom, Trout of the rocky 

 shores, and Trout of the open waters ; the first being a dull 

 mud-coloured fish, the second bright and handsomely mottled, 

 and the last bluish and silvery, and resembling more a clean-run 

 Salmon than a Lake Trout. 



This is so fairly a case in point, that I cannot resist quoting 

 it here, as it is perfectly evident that there is no real distinction 

 whatever ; and if this be so of one variety or species, there is no 

 reason for doubting that like causes will produce like effects, in 

 the congenerous species. Again, it is not only possible, but in 

 the highest degree probable, that the different chemical sub- 

 stances which are held in solution by the waters of various 

 streams and lakes may not be without their influence on the 

 the colouring of their inhabitants. I think I have myself 

 observed, both on this continent and in Europe, that the Trout 

 in streams flowing from lime-stone formations are more lus- 

 trous, and more strongly spotted than those of duller and less 

 lively waters. 



That the fish of streams rushing rapidly over pebbly beds 

 are superior in all respects, both of appearance and quality, to 

 those of ponds or semi-stagnant brooks, is confessedly noto- 

 rious ; but this may arise not so much from any particular 

 components of the waters themselves, as from the fact that 

 rapidly moving and falling water is more highly aerated, the 

 atmosphere being more freely intermingled with it, and there- 



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