62 The Natural History of the Salmon. 



were really young migratory salmonoids ; or that 

 the full-grown specimens were identical with those 

 introduced, and not hybrids or non-migratory trout 

 of a somewhat altered appearance, in consequence 

 of the change of their locality. We have seen the 

 experiment tried at two places in South Wales, and 

 in both cases the Salmon and the pure Sewin died, 

 when not allowed to return to the sea. On the 

 other hand, hybrid fishes from the Sewin and the 

 Trout survived the experiment, and continued to 

 grow in a pond perfectly shut up from communica- 

 tion with the sea. In that locality neither those 

 hybrids nor the trout spawn. 1 



" 4. Although the majority of the mature indivi- 

 duals of a migratory species ascend a river at a 

 certain fixed time before the commencement of 

 spawning, others enter the fresh water at a much 

 earlier period, either singly or in small troops, 

 and many appear to return to the sea, before 

 they reascend at the time of the regular immi- 

 gration. 2 It is not improbable that one and the 



1 Sea trout, S. trutta, can certainly live and propagate 

 their species in land-locked lakes. The experiment in the 

 Island of Lismore distinctly proves this. (H.) 



a Salmon begin ascending all the larger rivers, as early 

 as February, but chiefly in March, and fresh fish are con- 

 stantly ascending (and perhaps descending again) up to the 

 end of September ; in some rivers, the Tweed for example, 

 even much later. (H.) 



