irn. F. DAT ON BBlTTSn SALMOXES. 407 



■wkile sucli diet, as a rule, is rejected by the common variety of 

 Salmo fario, it appears to point out that the tastes of some differ 

 from those of their companions ; Avhile it is a Avell-knoAvn lact 

 that certain forms of food promote fish-growth more rapidly than 

 others. Mr. Stoddart gives the result of an interesting experi- 

 ment on trout : — " Fish were placed in three separate tanks, one 

 of which was supplied daily Avith worms, another with live 

 minnows, and the third Avith those small dark-coloured water-flies 

 Avhich are to be fouiid moving about on the surface under banks 

 and sheltered places. The trout fed on Avorms greAv sloAAdy, and 

 had a lean appearance ; those nourished on minnoAvs (AA'hich, it 

 Avas observed, they darted at AAdth great voracity) became much 

 larger ; A\diile such as were fattened upon flies only, attained in a 

 short time prodigious dimensions, Aveighing tAvice as much as both 

 the others together, although the quantity of food sAvallowed by 

 them Avas in noAvise so great." 



If a trout, normally belonging to a small race, as S. cornu- 

 hiensis, is transferred to a reservoir or lake where food is plen- 

 tiful, it attains a size to Avhich it never reaches in its ancestral 

 stream, shoAAdng capacity for growth to be inherent, and called 

 into action by luxuriant living. In 8cotland the largest ex- 

 amples are in lochs, so also in Wales and Ireland — although 

 occasionally a large one may be found existing in a sluggish 

 stream, especially if such passes over a rich soil. Should food 

 be plentiful, a brook-trout may attain to many pounds AA^eight 

 in suitable localities — in fact, to as large a size as the great lake- 

 trout, AA'hich I hold to be merely a form of/S.fario which indulges 

 in luxurious liA'ing or cannibal propensities. 



The first so-called species AA'hich I propose alluding to is Salmo 

 nigripinnis, Giinther, 1865, or S. cornuhiensis as described by 

 Borlase, Artedi, &c., and AA'hich for many reasons may be cou' 

 sidered the j^ouug of S. ferox. I have been most liberally 

 supplied AA'ith specimens from Cardiganshire, throiigh the kind- 

 ness of Sir Pryse Pryse ; and among them is one form which Avas 

 alluded to by Barringtou, in the ' Transactions of the Eoyal 

 Society ' for 1774, as the " Hog-backed Trout of Plinlimmon," 

 which Dr. Giinther, as I believe correctly, considered identical 

 Avith his ^S'. ni(jripinnis. My example is a peculiarly interesting 

 one, as shoA\dng a link between 8. nif/rijnnnis and iS.ferox^ per- 

 taining partially to one form and partially to the other. The 



