528 TEN YEAES IN SWEDEN. 



slightly altered by a long permanent residence in the fresh 

 water, to which it has been restricted. 



There is much in this remark, and I think very probably 

 that such may be the case. That Malmgren's opinion coin- 

 cides with it, is certain, for after describing the 8. trutta, L., 

 as a distinct species, he gives us Var. B. Trutta laeustris, 

 Sieb ; 8. ferox, Jard. ; 8. trutta, Agass. ; 8. ferox, Nilss. ; 

 8. microps, Hard. ; 8. trutta, Widigren (sterile form) ; 8. 

 Schieffermulleri, Bl. ; 8. laeustris, Agass. ; 8. laeustris, Heck, 

 and Kor. (sterile form, according to Widigren) ; Insjo forell, 

 Sw. And he remarks : " As the trutta relicta (vide next 

 description) is in the Lake Ladoga a confined form of the sea 

 salmon (8. salar, L.), so is it fair to suppose that this fish is 

 a confined form in our inland lakes, of the sea trout (8. 

 trutta, L.) 



' ' Most icthyologists consider this a distinct species, al- 

 though we have not had the luck as yet to prove it so by 

 any certain distinguishing marks. According to my judg- 

 ment, it is as impossible to consider this and the following 

 variety" (he here alludes to the common trout, S.fario, L.) 

 ' ' as true and well defined species, as it is wrong to follow Dr. 

 Widigren, and reduce them altogether to one single species, 

 without noticing or accounting for the different forms in 

 which this species is met with in nature. The distinguishing 

 marks of this variety are its stronger teeth and darker body 

 colour, especially above. They live in most of our large 

 Finnish inland lakes, such as Ladoga, etc., out of which they 

 ascend the rivers to spawn. 



' ' Siebold, who considers both this and the 8. fario, L., 

 as good species, gives as one of the specific differences in 

 this fish that it has larger scales than the sea trout (8. 

 trutta, L.) ; but we can lay little stress on this, because the 

 scales vary so much in size even in members of the same 

 form. The stronger teeth in the f insjo forell' are 

 accounted for by the fact that this fish principally lives on 

 smaller fish, whereas the salmon trout (hafs forell) lives on 

 smaller animals, principally Crustacea, for the seizing of 

 which strong teeth are not required. Between our speci- 



