240 
GILLAROO. 
GIZZARD TROUT. 
Gillaroo Trout, Thompson ; Nat. Hist, of Ireland, vol. iv, p. 154. 
The Gillaroo is usually set douai as a variety of the Common 
Trout, from which the ordinary supposition has been that it 
is only distinguished by a particular firmness, or gizzard-like 
structure of the coats of the stomach; and it has been further 
believed that this thickness of the stomach is caused by its 
habit of feeding on shell-fish or other hard substances. Of the 
particular structure of this organ we shall presently give an 
account; but the alleged cause appears the more doubtful, as 
it is found in this fish in its very young condition, and the 
ordinary Trouts which inhabit the same rivers, and at least 
occasionally devour the same substances, are without this par- 
ticular form of the organ. It appears that the fishermen are 
well able to distinguish between the Gillaroo and the Common 
Trout; and, for myself, (having been favoured by the kindness 
of the noble Earl of Enniskillen, whose promptitude in fur- 
nishing me with supplies of this and other fishes of Ireland 
demands my earnest acknowledgments,) from a close examination 
of them I feel no hesitation in expressing my opinion that 
this is a distinct species from the Common Trout; and in this 
it is a satisfaction to find myself supported by Mr. Thompson 
in the work above referred to. That the instinct of this fish 
may lead it to feed more freely on river shell-fish than the 
Common and Lake Trouts which frequent the same rivers, is 
hic^hly probable; and it is probably better able than they 
to'’ crush and digest them; but it also takes freely a fly 
and worm, and it is to be regretted that its other more 
peculiar habits have not hitherto been closely studied. It is 
