284 Salmon-Fishing. 



haustive examination of all these external charac- 

 teristics, one should still be at a loss to say whether 

 the fish he has caught he a salmon, a bull-trout, 

 or a sea-trout, nothing remains but to adopt the 

 method Josh Billings suggests for settling, at once 

 and for ever, whether a certain fungus is a mush- 

 room or a toad-stool let him eat it and he will see. 

 Though the result of the experiment with the fish 

 would certainly not be so serious as that with the 

 fungus, it would be quite as conclusive ; for no one 

 would fail to detect the bull-trout, when cooked, by 

 its markedly inferior taste. Nevertheless, they are 



ichthyologist with regard to the distinction of the species , as well 

 as to certain points in their life-history. " Some naturalists, such 

 as Couch, reckon a vast number of species ; but it is more than 

 probable that many of these so-called species are merely varieties 

 of the same fish, arising from changes in the external conditions 

 of its existence. Dr Day, in his ' Fishes of Great Britain and 

 Ireland ' (vol. ii. p. 59), is clearly of this opinion ; and, with 

 special reference to the Salmo trutta, says : " It is evident that 

 our anadromous sea-trout may take on a fresh-water state of 

 existence, and breed there (as in the Lismore experiments), irre- 

 spective of which, by imperceptible changes, we find it in every 

 country passing from one form to another. " 



Hybridism, too, has no inconsiderable share in increasing the 

 varieties. According to Giinther, " Abundant evidence has accu- 

 mulated, showing the frequent occurrence of hybrids between the 

 S. fario (common river-trout) and the S. trutta (sea-trout) ; " and 

 "it is characteristic of hybrids that their characters are very 

 variable, the degrees of affinity to one or other of the parents 

 being inconstant; and as these hybrids are known readily to 

 breed with either of the parent race, the variations of form, 

 structure, and colour, are infinite," 



