64 SALMONIA. 



these flies on stagnant waters and lakes, 

 which form a part of the food of various fishes, 

 principally of the carp kind: but the true fish- 

 erman's flies — those which are imitated in 

 our art — principally belong to the northern, or 

 at least temperate part of Europe, and I believe 

 are nowhere more abundant than in England. 

 It appears to me, that since I have been a 

 fisherman, which is now the best part of half 

 a century, I have observed, in some rivers 

 where I have been accustomed to fish habit- 

 ually, a diminution of the numbers of flies. 

 There were always some seasons in which the 

 temperature was favourable to a quantity of 

 fly ; for instance, fine warm days in spring for 

 the grannam, or brown fly ; and like days in 

 May and June for the alder-fly, May- fly, and 

 stone-fly ; but I should say that within these 

 last twenty years I have observed a general 

 diminution of the spring and autumnal flies, 

 except in those rivers which are fed from 

 sources that run from chalk, and which are 

 perennial, — such as the Wandle, and the 

 Hampshire and Buckinghamshire rivers ; in 

 these streams the temperature is more uni- 



