SALMONIDk. 41 



ratus by means of which the fish breathes ; in other words, by which 

 the oxygen is separated from the water, in which the animal exists, as 

 it enters by the mouth and passes out at the aperture of the gills, con- 

 veying its influence to the blood in its passage. 



This apparatus being of course of the highest degree of importance 

 to the animal, varies in form aad structure according to the various 

 exigencies of the different species to which it is attached ; and if is 

 therefore of great value to the observer in distinguishing one family, 

 and even one species of the same family, from another. 



With regard to the family of which we are now treating, the Sal- 

 monida, beyond all (juestion the most important and most interesting 

 to the sportsman, as being the gamest, boldest, and strongest of all 

 the fish with which he has to do, and to the epicure likewise, as afibrd- 

 ing the greatest varieties of the most delicious food, the remarks I am 

 about to make have especial application. 



Of no other family known to the sportsman, are the species so 

 numerous, and so diflGicult of definition ; and not only the truly distinct 

 species, but the subordinate varieties, produced in the same species 

 by difference of food, of water, of bottom-ground in the lakes or rivers 

 haunted by each, and even b;^ the degrees of light or shadow which 

 affects the localities which they haunt. These varieties, often differ- 

 iDQg by many pounds' weight, colors in the broadest sense of the word, 

 not tints or shades t)f hue, quality of flesh, and shape, are by no means 

 to be set down as distinct and permanent species ; for it will be found 

 that a transposition of these from one place to another, and even the 

 regular course of reproduction, will bring them baek to the original or 

 normal type. 



What strikes us, moreover,, at first sight, as in no small degree 

 angular, is the fact, that different varieties of one species will very 

 frequently differ more widely from one another, and from the original 

 type, so far as those externals whioh strike the mere superficial obser- 

 ver, than entirely distinct and immutable species. 



This it is which so often leads common and vulgar-minded persons, 

 who are in the habit of boasting that they believe their own eyes only, 

 and resorting to, other absurdities of that kind, and who will not take 

 the trouble of connecting causes and effects, or considering logical 



