LOCALITIES OF FISHES. 89 



But if the natural means by which the species 

 inhabiting: the continuous waters of the ocean have 



O 



spread themselves from clime to clime, be to a 

 certain extent within the range of our comprehen- 

 sion, it is otherwise with those peculiar to rivers, 

 and the waters of secluded lakes. How these have 

 contrived to migrate from one region to another, 

 and to people with identical species the depths of 

 far removed and solitary waters, separated from 

 each other by chains of lofty mountains, or wide 

 extended wastes of desert sand, is a problem, which 

 in the present state of our knowledge we seek in 

 vain to solve. How came the vendace of Loch- 

 maben into certain Lochs in Dumfries-shire, and 

 into no others in England, Scotland, Wales, or the 

 emerald Isle 2 Why, or from whence, did Salmo 

 ferox descend into numerous Lochs in Scotland, 

 and continue absent from many others, equally 

 adapted (as it seems) to their reception, preserva- 

 tion, and increase? It may indeed happen that 

 spawn or ova are carried by water-fowl from one 

 great central reservoir to another, and thus the 

 rivers of a half a continent may be put in possession 

 of species unknown before ; but this supposition 

 scarcely suffices to account for the general diffusion 

 of certain species, and still less for the narrow 

 restriction of others, equally subjected to the chances 

 of that aerial flight. 



We now proceed to a detailed, though not greatly 

 extended sketch of the various species of fishes 

 which fall within the range of angling art, in- 



