Natural History of the River Trout. 171 



varies considerably in appearance in different locali- 

 ties so much so as to have induced the belief that 

 several species exist. It is, indeed, probable that 

 more than one species of river trout may exist in 

 this country ; but when we consider geologically 

 the various strata traversed by rivers in their 

 course, the effect these variations of soil may pro- 

 duce upon the water, and the influence which the 

 constant operation of the water is likely to produce 

 on the fish that inhabit it ; when we reflect, also, 

 on the great variety and quality of the food afforded 

 by different rivers, depending also on soil and 

 situation, and the additional effect which these 

 combined causes in their various degrees are likely 

 to produce, we shall not be much surprised at the 

 variations, both in size and colour, which are found 

 to occur. That two trout of a very different appear- 

 ance and quality should be found within a limited 

 locality, in the same lake or river, is not so easily 

 explained ; and close examination of the various 

 parts which afford the most permanent characters 

 should be resorted to, with a view to determine 

 whether the subject ought to be considered only as 

 a variety or entitled to rank as a species." ' 



In "British Fresh-water Fishes," a costly and 



1 In the upper reaches of the Test the trout are large ; 

 about Whitchurch they are smaller; below Whitchurch, 

 larger ; and in Peter Hawker's Water very large. Why is 

 this ? (S. H.) 



