GENERAL FEATURES 6i 



Nor can it be said that the test of the scales will prove final as a 

 distinction between sea-trout and trout, for the concentric rings of 

 growth are added to the scales of the sea-trout exactly in the same way 

 as in the case of the trout, while both f:sh remain in their earlier stages 

 of growth in fresh water. No doubt an immediate distinction takes 

 place as to the scales of the sea-trout when that fish migrates to the 

 sea, the rings of growth which are then added being comparatively wide 

 apart, so that the salt-water series of rings contrasts strongly with the 

 fresh-water series. But the same kind of distinction immediately 

 occurs in the rings of growth of the scale of a trout when by chance it 

 happens to change its quarters from an ill-provided and circumscribed 

 hill stream or tarn to a rich and extensive lake. 



I am far from wishing to appear dogmatic on this still somewhat 

 theoretical question of the identity of the sea-trout and trout — or, I 

 should perhaps put it, certain sea-trout and trout — but the fact has 

 apparently to be faced that it is not very easy to discover any such 

 characteristic structural differences between the fish as would warrant 

 their systematic classification in distinct groups. 



Turning now to another matter, it is not always easy, with fresh-run 

 sea-trout, to distinguish the male from the female. The distinction 

 becomes more marked as the spawning season approaches, for then the 

 male fish becomes reddish coloured and the female, as a rule, a dingy 

 grey. But if, on firmly closing the mouth of any sea-trout, it is found 

 that the under jaw closes well within the upper, the fish may be 

 pronounced a female. If not, it is more probably a male, and at 

 spawning time, or, in the case of old fish, at any time, a more or less 

 well developed " hook " will be found on the lower jaw (see Figs. 13 

 and 14) which emphasises its length relatively to the upper. An 

 autopsy will, of course, always disclose the sex. 



There is still the question to be considered whether, in respect of 

 the migratory trout, there is sufficient warrant for making a distinction 



