272 KNUT DAHL. 



Needless to say, only fishes whose anal fin was quite unin- 

 jured have been employed in the construction of this table. The 

 main difference in shape consists in the caudal fin of the sal- 

 mon having long and more pointed flukes than that of the trout. 

 Also the basal part of this fin is less broad in the salmon 

 than in that the trout. 



Respecting the size of the scales vide tab. I. 



The colour at this stage, at least in more advanced de- 

 velopment, differs considerably from that of the emigration 

 stage. The metallic lustre in both species gradually gets more 

 prominent as the juvenile markings more and more disap- 

 pear. The undercolouring in the salmon is still blueish-green, 

 while that of the trout is more brownish-green. 



In the case of the trout however, great variations occur ac- 

 cording to surroundings. The salmon however, seems to be 

 constant in this respect. 



The trout possesses a large number of black spots, densely 

 distributed. These spots extend far below the lateral line as 

 well in front, as behind a perpendicular line drawn downwards 

 from the posterior base of the dorsal fin. 



The black spots of the salmon on the contrary, are very 

 few and large, and only a few are found below the lateral line. 

 Very rarely do black spots occur below the lateral line behind a 

 vertical line drawn downwards from the posterior base of the 

 dorsal fin. The black spots below the lateral line are mostly 

 hmited to the triangle produced by a line drawn from the upper 

 base of the pectoral fin to that point in the lateral line, where 

 a perpendicjjlar fine drawn from the posterior base of the dorsal 

 fin would cut the lateral line. 



g. Capture of -young salmon in the ocean. 

 The positive material I have succeeded in procuring to 

 illustrate the habitat of the young salmon between the emigration 

 stage and the grilse slage is not very large. 



