244 THE ANGLEE-NATUEALIST. 



1. The Silver, or Migratory species (i.e. those migrating 

 to and from the sea) ; 



2. The Yellow, or Non-migratory species ; and, 



3. The Charrs, or Orange- and Red-coloured species. 

 Between these three groups no difficulty can well arise, 



the general colour of the first being always more or less 

 greyish-silver, that of the second golden or yellow, and 

 that of the third, especially on the under part of the body, 

 crimson and orange of various degrees of brilliancy. Dis- 

 missing here, therefore, the last two groups, to be again 

 referred to in their proper order, I shall restrict myself at 

 present to the first group only — viz. the Silver, or Migra- 

 tory species. 



These are three in number ; and they include, according 

 to the opinions of the most eminent ichthyologists, the 

 whole of our migratory Salmonidm, under whatever local 

 names they may occur. 



They are : — 



The true Salmon (Parr, Smolt, Grilse) — Salmo salar; 

 The BuU- Trout (also called Grey Trout, Sewin, and 



Roundtail) — Salmo eriox; and 

 The Sea- Trout or Salmon- Trout — Salmo trutta. 



We now come to the specific distinctions between these 

 three fish, which, as their general colour and appearance 

 are very similar, will be illustrated by reference (1) to the 

 form of the gill-covers, (2) to the number and situation of 



tions in regard to kabit, structure, &c., as must override distinctions 

 founded upon any mere technical differences. 



