A STUDY ON TROUT AND YOUNG SALMON. 



263 





Length. 



Scale-figure, 



Tail- 

 coefficient L 



Tail- 

 coefficient II. 



Nr. 1 . . . . 



17 cm. 



13 



0,85 



1,91 



„ 2. .. . 



39 „ 



14 



1,57 



2,32 



„ 3 . . . . 



49 „ 



15 



1,33 



— 



„ 4 . . . . 



88 „ 



13 



1,00 



— 



„ 5 



108 „ 



13 



0,92 



- 



In the face of my experiences I will however not deny the 

 possibility that an examination of still larger numbers of indi- 

 viduals might produce salmon or trout which in all 3 relations 

 possess values corresponding to those values of the curves, 

 which are common to both species. 



As I have not in the sifting of my relatively large amount 

 of material met with such specimens, the conclusion however 

 seems justifiable, that such specimens are extreemely rare. 



In all the cases examined, the total of the values of these 

 3 different relations combined, always points clearly in the direc- 

 tion of one or the other of the two species. 



Thus the examination of these 3 characters, yields a good 

 means of specific distinction. In most cases it is quite sufficient, 

 and when other characters are also taken into consideration, 

 there is no room for error. 



e. Description of young salmon and trout. 



The distinction between the young of salmon and trout at 

 that stage of developement, when they leave the rivers, is effec- 

 ted by means of the differences observable in the form and 

 relations of the body — those of the head, the size and form of 

 the scales, the colour, and, when the fish is living, its habits. 



