The Natural History of the Salmon. 5 5 



lakes with pebbly bottom the fish are bright silvery 

 and the ocellated spots are generally mixed with or 

 replaced by X-shaped black spots ; in pools or parts 

 of lakes with muddy or peaty bottom, the trout are 

 of a blacker colour generally, and when enclosed 

 in caves or holes they may assume an almost uni- 

 form blackish coloration. 



" The change of scales (that is, the rapid reproduc- 

 tion of the worn part of the scales) coincides in the 

 migratory species with their sojourn in the sea ; the 

 renovated scales give them a bright silvery appear- 

 ance, most of the spots disappearing or being over- 

 laid and hidden by the silvery scales. Now some 

 of the species, like Salmo fario (the common trout), 

 inhabit all the different waters indicated, 1 even 

 brackish water ; and in consequence we find a great 

 variation of colour in one and the same species; 

 others are more restricted in their habitat, like S. 

 salar and 5. ferox, etc., and therefore their coloration 

 may be more precisely defined. 



" With regard to size, the various species do not 

 present an equal amount of variation. Size appears 



1 Fine specimens of what are supposed to be sea trout 

 are sometimes caught in the smelt nets at the mouth of the 

 Medway. They are in splendid condition, and as silvery as 

 a salmon. Are they not the Salmo fario, altered in colora- 

 tion and appearance owing to the brackish water ? See p. 69. 

 (H.) 



