2 SALMONID.E. 



of the world, in proportion to its size, are tlie fisheries so 

 extensive, or the value of so much importance, as in the 

 United Kingdom. 



The history of the Salmon, and of the species of the 

 genus Salmo, in this work, will extend to a considerable 

 length ; and some doubts existing as to the extent of their 

 identity with the species of the Salmonidae generally which 

 are taken in the rivers or lakes of other countries of Europe, 

 from the want of specimens with which to make actual 

 comparative examination, the account of the species here 

 inserted will be confined more particularly to a detail of 

 what is known of them in this country only. 



Of the species existing in this country, the characters and 

 specific distinctions admit of considerable detail' : too much 

 reliance has been placed upon colour, without resorting 

 sufficiently to those external indications, founded on organic 

 structure, which may with greater certainty be depended 

 upon. 



In the scale of the relative value of parts affording cha- 

 racters for distinction, the organs of digestion, respiration, 

 and motion are admitted by systematic authors to hold 

 high rank ; and in the hope to induce sportsmen to become 

 zoologists — so far at least as to enable them to determine 

 the various species they may meet with by a reference to 

 those external characters which are the most important, — ' 

 the specific distinctions in the genus Salmo will be illus- 

 trated by referring to the number and situation of the 

 teeth, the form of the different parts of the gill-covers, 

 and the size, form, and relative situation of the fins. 



The outlines here introduced represent a front view of 

 the mouth, and a side view of the head, of a common 

 Trout. Of the first figure on the left hand, No. 1 marks 



