200 



SALMONID^ OF BRITAIN. 



Dr. Hamilton, v.P.z.s., communicated to me the following interesting facts 

 which came under his immediate observation in 1882. In the year 1867 two 

 separate lochs in Scotland were stocked with trout taken from Loch Morar. One of 



these latter localities was 

 situated on a hill, Ci-aig- 

 moor, Inverness-shire, 1500 

 ft. above sea level, it being 

 a mile and a half in cir- 

 cumference, and possess- 

 ing a sandy and weedy 

 bottom. Here the fish 

 never attain to a pound's 

 weight, but are long and 

 lanky, rise freely to the 

 fly, and give good sport 

 to the angler. Externally 

 their sides and under sur- 

 face have a golden tinge, 

 while they are covered 

 with numerous red spots ; 

 having been cooked the 

 flesh cuts white. A female 

 10| in. long, examined in 

 The fish are very game, and rise boldly 



Fig. 47. Csecal appendages 

 49, and also cystic duct of a 

 brook trout from the Wind- 

 rush, 5 natural size. 



1882, was found by Dr. 

 Hamilton to have only 

 twenty - seven coccal ap- 

 jiendages, while the length 

 of the head was equal to 

 the height of the body, or 

 5|- in that of the total 

 length. The tail fin was 

 nearly square at the 

 extremity. The second 

 locality, also stocked in 

 1867 from the same loch, 

 and termed Loch Sheau 

 More, Arisaig, Inverness- 

 shire, is smaller than the 

 preceding one, and not 

 very deep, but the water 

 is dark - coloured, while 

 the bottom appears to be 

 covered with small rocks. 

 The head is very dark, nearly black. 



the sides yellowish olive, and the eyes prominent. A few (about ten) red spots 

 are present on each side, and thirteen to fourteen black ones ; having been 

 cooked the flesh is yellowish pink. Dr. Hamilton examined a female lOi in. 

 long, and found forty csecal appendages, while the length of the head was 

 one-sixth, and the height of the body one-quarter of the total length. The 

 tail fin was nearly square at its extremity. Here we observe the progeny of 

 trout transferred from a single piece of water. Loch Morar, in 1867, had so 

 altered by 1882, due to changed conditions of life, that they would be distinct 

 species as recognized by some naturalists. If the difference of living in these 

 two localities sets up such changes that only twenty-seven csecal appendages are 

 developed in one form and forty in the other; that the depth of the body is 

 nearly one-sixth of the length in the first, but a quarter in the second ; if one 

 possesses numerous red spots, while the second has but few, but many black ones, 

 it does not appear that we need go so far as Tasmania to prove how inconstant in 

 trout are external colours or form, as well as the inadmissibility of accepting the 

 number of cKcal appendages as a basis for forming species. 



Colours. — Among trout inhabiting fresh waters and estuaries large differences 

 in the tints and markings are perceptible as might be expected* (pp. 6, 144, 145). 

 In short, as has been already referred to, w^e may perceive fresh-water forms 

 approaching sea troiit in colour as those of Loch Crasspuil (p. 190), and of which 

 occasional examples may be seen in Loch Lomond and elsewhere. While there 

 are many circumstances alfecting colour, as the state of health of the fish, the 

 period of the year, if it is in a breeding condition, its age, the qualitj^ and amount 

 of food it can obtain, the character of the water and its siuToundings, and whether 

 the stream is rapid or sluggish. In some of the silvery forms there are merely 

 black spots which may be round, and are often encompassed by a light ring,t 



* St. John, Natural History and Sport in Moray, p. 2.5, observed, " Put a living black burn 

 trout into a white basin of ^Yater, and it becomes within half-an-hour of a light colour. Keep the 

 fish living in a white jar for some days and it becomes absolutely white : but put it into a dark- 

 coloured or black vessel, and although on lirst being placed there, the white-coloured fish shows 

 most conspicuously on the black ground, in a quarter of an hour it becomes as dark coloured as 

 the bottom of the jar and consequently difficult to be seen." 



t Sometimes black spots on these fishes become surrounded after death with a light ring, 

 while in others red spots may appear which were not seen when they were living. Also Bome fish 

 when not in good condition will lose their colours very rapidly. 



