ON THE GRAYLING. 21 



Temperature, both atmospheric and aqueous, 

 no doubt affects both the food and fish, as also 

 may the chemical properties of the stratum over 

 which the stream flows ; the mineral held in 

 solution by the fluid which he breathes cannot 

 fail to affect his constitution in some measure. 



But there exists no authority for the localities 

 of the Grayling at all comparable with Sir H. 

 Davy, who " has fished much in, and inquired 

 much respecting the places where it is found." 

 At p. 221 (Salmonia) he says : " In the Test, 

 where the Grayling has been only recently intro- 

 duced, they have sometimes been caught between 

 three and four pounds ; in this river I never took 

 one above two pounds, but I have heard of one 

 being taken of two pounds and a half. The 

 Grayling is a rare fish in England, and has never 

 been found in Scotland or Ireland ; and there are 

 few rivers containing all the conditions necessary 

 for their increase. I know of no Grayling river 

 farther West than the Avon in Hampshire ; they 

 are found in some of the tributary streams of 

 this river which rise in Wiltshire. I know of no 

 river containing them on the North coast West 

 of the Severn ; there are very few only in the 

 upper part of this river, and in the streams 

 which form it in North Wales. There are a few 

 in the Wye and its tributary streams. In the 

 Lug, which flows through the next valley, in 



