A STUDY ON TROUT AND YOUNG SALMON. 249 



of course renders is unfit for a description encompassing imma- 

 ture fishes, especially when this description, as in the case of 

 prof. Smitt, is founded on metrical characters. 



The facts here mentioned, besides the small number of the 

 specimens, are in my opinion well adapted to throw some light 

 on the difficulties which prof. Smitt has experienced in distin- 

 guishing the „forell" stages of salmon and trout. By comparing 

 certain metrical characters and demanding the continuity of these 

 characters through all stages as professor Smitt has done, the 

 difficulty is obsiously extended to the two species during the 

 whole of their developement. 



It is to me perfectly clear, that the introduction of only one 

 or two specimens in the mature stage, wil be sufficient to disturb 

 the final mean of metrical characters when the work is carried 

 out according to the system which prof. Smitt employes. 



It will be remembered that the proportions of as well salmon 

 as trout are considerably altered when in a state of sexual 

 maturity. 



It is just as evident, that a collection of a few individuals 

 of young Vener-salmon, cannot possibly form the base of a 

 diagnostic description of the young of the salmon of the ocean. 

 Also the trout-characters of these specimens would be higly 

 efficient in confusing a description, where even real salmon were 

 used as material. 



From the facts above mentioned, it must, as far as I can 

 see, follow that this material, and the descriptions based there- 

 on, hardly may be considered as rendering any satisfactory 

 contribution towards filling the gap, which, according to my ex- 

 perience, exists in the description of salmon between the emi- 

 gration stage and the grilse stage. 



The investigations of Hjalmar Widegren will be found de- 

 scribed in „Öfversigt af Kgl. Vetsk. Ak. Handlingar" 1862 and 

 1864 „Bidrag till kännedomen om Sveriges salmonider" and 

 „Nya bidrag til etc." 



