THE BULL TROUT. 291 



at all times the preference. Of the Bull Trout of Yarrell 

 there appear to be numerous varieties, differing, however, 

 not sufficiently from one another to be considered by ichthyo- 

 logists as deserving to rank as distinct species. The Bull- 

 Trout, when about nine inches in length, has the caudal fin 

 acutely forked ; the middle rays elongating with the growth 

 of the fish, and the fin ultimately becoming even at the end. 

 When the fish reaches the length of twenty inches, the mid- 

 dle ray of the tail is more than half the length of the long- 

 est ray of the same fin, whereas the same ray in the salmon 

 is never half as long as the longest ray of that fin at any 

 age, a character that may be strictly depended on. Mr 

 Yarrell places much dependence, as a character, on the 

 formation of the suboperculum, and its line of union with 

 the operculum compared to the axis of the body of the fish. 

 In some examples I have recognised this character, but in 

 others I have found it to vary too much to form a uniform 

 mark of distinction. In the Firth of Forth I have met 

 with the following varieties of Salmo Eriox : — 



(Plate XXXII. Fig. A.— Salmon-spotted Butt-Trout.) — Length 

 twenty-seven inches ; female ; four teeth on the anterior part of the 

 vomer ; basal margin of the operculum very oblique ; tail even at the 

 end, six spots below the lateral line, twenty-eight above it ; flesh 

 red ; caeca fifty-four. Salmon-Trout of the Firth of Forth, Sol way 

 Firth, and at Berwick-upon-Tweed ; in the latter locality it is fre- 

 quently named Whitling. 



(Plate XXXIII. Fig.5. — Few-spotted Bull-Trout. — Length twenty- 

 five inches ; female ; two teeth on the anterior part of the vomer ; 

 suboperculum very narrow ; basal margin of the operculum oblique, 

 in a line with the summit of the first dorsal ray ; preoperculum 

 sinuous ; tail slightly forked ; no spots below the lateral line, and 

 only four obscure ones above it ; flesh deep red, caeca fifty-five. 

 Salmon-Trout of the Firth of Forth, Sol way Firth, and Tweed, 

 rather rare. 



(Plate XXXIII. Fig. 6.— Thickly-spotted Bull-Trout.— -Length 

 twenty-four inches ; female ; one tooth on the vomer; suboperculum 

 narrow, produced at its upper and posterior margin ; preoperculum 



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