KNUT DAHL. 



also have dealt with them. Among the swedish investigators 

 the principal ones are Nilsson, Widegren, Liljeborg, Fries 

 Ekström and Sundewal, besides F. A. Smitt. I will not here 

 in detail pursue the fate of Linnés 5 species under the hands 

 of all these men. 



His first species, the salmon, Salmo salar, has endured all 

 trials; contrary to this his 4 species of trout have encountered 

 very variable conditions. The great variation among trouts, 

 which is the fundament of Linnés species has on closer study 

 made the distinction between species and non species very diffi- 

 cult. As every one knows, who has paid attention to these 

 things, the trout of even closely connected waters, may differ 

 considerably in certain respects, for instance in colour and the 

 form of the body. To begin with, this circumstance caused 

 the proposition of still more species than Linné originally did 

 propose. 



However on this fundament there would apparently be no 

 end to the constitution of new species and very soon we notice 

 a tendency to reduce the number of species, a closer investi- 

 gation showing that the peculiarities whereon the descriptions 

 of the species were founded mainly were peculiarities which 

 every trout under given circumstances could acquire. 



The latest swedish naturalists, f. ex. Liljeborg, nominate 

 now only two species: 



Salmon [salmo salar). 

 Trout [Salmo trutta). 



Still more exacting in his reduction is F. A. Smitt, who 

 only nominates one species, salmo salar, and as a variety 

 thereof s. trutta. 



LiLjEBORG thus asserts, that the proper sahiion [salmo 

 salar) in all stages of its life may be distinguished fi-om any 

 other salmonid form. 



The Trout [salmo trutta), which is found in the fi-esh 

 waters as well as in the sea, varies highly and he does not find 



