NATURAL HISTORY OF BRITISH SALMONIDE. 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. 
Giinther—that there is enough evidence for considering Sa/mo 
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. Giinther, 
are probably due to the abundance of 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. That, at least, is my opinion. 
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. I have caught scores in Lough Melvin, and 
examined the so-called ‘gizzards’ of many, and I invariably 
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 cca from 60 to 80. 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 
g round dark spots ; body above lateral line with 7o spots, below it 10; back fin thickly 
inarked 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: P12: V.g: A. 10: C. 19. 
‘These fish,’ says Dr. Parnell, ‘do not appear to be peculiar to Loch Leven, 
as I bave seen specimens that were taken in some 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 furio, 
and which remain to be further investigated, 
I. M 
