NATURAL HISTORY OF BRITISH SALMONID&. 161 



was myself formerly of opinion, without perhaps sufficiently close 

 examination, that there was probably ground for the distinction, 

 but> having since visited Loch Leven and examined a large 

 number of its trout, I really do not think with great deference 

 to the authority of so distinguished an ichthyologist as Dr. 

 Gunther that there is enough evidence for considering Sal/no 

 levenensis as other than a variety and, it must be admitted, 

 a very beautiful and 'sporting' variety of the common trout. 

 Its excellent flavour and sporting qualities, as well as, very pos- 

 sibly, the more permanent differences noticed by Dr. Gunther, 

 are due to the abundance of small red shell fish on which it to 

 a great extent exists. Some ichthyological authorities would 

 make a distinct species out of the Gillaroo trout, &c., but 

 the fact is all these variations are produced by the wonderful 

 'plasticity' of nature in adapting fish, as well as other animals 

 to the conditions of climate, food, &c., in which they have to 

 exist. 



The remarkable variation, for example, in the Gillaroo con- 

 sists in the thickening of the coats of the stomach, so as to 

 afford increased muscular power for dealing with its peculiar 

 shell-fish food. It has been said to be recognised in Lough 

 Neagh, the largest of the Irish lakes, as well as Loughs Boffin, 



when expanded ; in common rounded. Tail fin long, rather narrow, and concave at the 

 end. Tail-fin rays much longer than in the common trout, and pointed at the upper and 

 lower extremities, whilst in the latter they are rounded. Teeth stout, sharp, and 

 curved slightly inwards, situated as in the common trout. In the specimen described by 

 Dr. Parnell there were 32 in the upper jaw, 18 on the lower, 12 on each palatine bone, 

 13 on the vomer, or central bone in roof of mouth, and 8 on the tongue. Scales small, 

 thick, and adherent, when dry exhibiting a small ridge in the centre of each, not perceived 

 in the common trout ; 24 in an oblique row between middle back-fin ray and lateral line. 

 Pyloric ca;ca from 60 to So. Colours: back deep olive green; sides lighter; belly 

 inclining to yellow ; pectoral fins orange, tipped with grey ; back- and tail-fins dusky ; 

 ventral and anal fins lighter. Gill cover (in the specimen described by Dr. Parnell) with 

 9 round dark spots ; body above lateral line with 70 spots, below it 10 ; back fin thickly 

 marked with similar spots. Foreign extremities of anal and back fins without the 

 oblique dark bands so constant and conspicuous in many of the common trout. Flesh 

 deep red. The Loch Leven trout has never any red spots, and the common trout is 

 scarcely ever without them. Fin rays : D. 12 : P. 12 : V. 9 : A. 10 : C. 19. 



'These fish,' says Dr. Parnell, ' do not appear to be peculiar to Loch Leven, 

 as I have seen specimens that were taken in iorne of the lakes in the county of 

 Sutherland, with several other trout which were too hastily considered as mere 

 varieties of Salmo fario. It is more than probable that the Scottish lakes 

 produce several species of trout known at present by the name of Salmo fariu, 

 and which remain to be further investigated. 



I. M 



