316 THE ANGLER-NATURALIST. 



To return to the Common Trout : This species is so 

 well known, and is so widely distributed over the whole 

 of the British Islands and the Continent, as to make any 

 description of its appearance or habitats superfluous. In- 

 deed, to give a complete account of the former would 

 occupy a dozen folios, as its colours and shape except in 

 the points already referred to are susceptible of infinite 

 difference, and vary as much as the qualities of waters 

 (whether in sources or feeders), geological strata of the 

 beds, and nature and quantity of food supplied by the 

 brooks, streams, rivers, ponds, lynns, and lakes in which it 

 is bred. This diversity of colouring is, in fact, a defence 

 furnished by nature for the preservation of the fish, which 

 would otherwise be so plainly visible upon the slightest 

 change of water or soil as to fall an easy prey to its ene- 

 mies, whether biped or quadruped ; and experiments have 

 shown that the change is a question of minutes rather than 

 of days or weeks. Upon its transfer from a light- to a 

 dark-coloured vessel, or vice versd, the hue undergoes an 

 instant alteration, and in a very short time assimilates itself 

 more or less perfectly to that of its new domicile. This is 

 also the case, though perhaps in a less remarkable degree, 

 with the Salmon and all other species of river and sea fish. 

 Thus, for instance, the Trout of Lynn Ogwin, almost the 

 whole bottom of which is formed of grass, have when first 

 caught a brilliant emerald gloss over their golden and 

 yellow tints ; and although the waters are of the utmost 

 clearness and the lake swarming with fish, I was never able 



