VARIETIES OF TROUT. 71 



pose in June, and continuing to do so all 

 the summer ; and this river is fed by streams 

 from snow and glaciers in the Tyrol, and 

 is generally foul: whilst the small spotted 

 common trouts, which are likewise found in 

 this lake, go into the small brooks which 

 have their sources not far off, and in which 

 they were probably originally bred. And 

 I have seen taken in the same net small 

 fish of both these varieties, which were as 

 marked as possible in their characters: 

 one silvery, like a young salmon, blue on 

 the back and with small black spots only ; 

 the other, with yellow belly and red spots, 

 and an olive-coloured back. I have made 

 similar observations in other lakes, parti- 

 cularly in that of the Traun near Gmimden, 

 and likewise at Loch Neah in Ireland. In- 

 deed, considering the sea trout as the type 

 of the species trout, it is, I think, probable 

 that all the other true trouts may be con- 

 sidered as varieties, where the differences 

 of food and of habits have occasioned, in a 

 long course of ages, differences of shape and 

 colours, transmitted to offspring in the same 



