THE SALMON FAMILY. 317 



in any one instance to distinguish these from their sur- 

 rounding green. Again, in the Spean Water, Inverness, 

 there are several small tarns in which I have frequently 

 taken fish of almost the colour of ink; yet these tarns 

 actually join the Spean, where many of the Trout are of a 

 fine rich yellow, the cause of the difference being that the 

 river has at this point a bed of gravel, whilst the tarns are 

 floored with a deep deposit of black mud. A similar pecu- 

 liarity has been noticed as regards the black-moss Trout 

 of Loch Knitching; and Loch Katrine produces a small 

 description of very dark Trout, which probably owe their 

 discoloration, as in many other lochs, to the drainage of 

 bog-moors. 



A remarkable example of this variation is given by the 

 author of ' Wild Sports of the West/ " I never observed/' 

 he says, " the effect of bottom- soil upon the quality of fish 

 so strongly marked as in the Trout taken in a small lake 

 in the county of Monaghan. The water is a long irregular 

 sheet of no great depth, one shore bounded by a bog, the 

 other by a dry gravelly surface. On the bog side the Trout 

 are of the dark and shapeless species peculiar to moorish 

 loughs, whilst the other affords the beautiful and sprightly 

 variety generally inhabiting rapid and sandy streams. 

 Narrow as the lake is, the fish appear to confine themselves 

 to their respective limits, the red Trout being never found 

 upon the bog moiety of the lake, nor the black where the 

 under-surface is hard gravel." 



Although, however, in all these cases the variations in 



