226 
COMMON TROTJT. 
especially in colour and habits, which has suggested the question 
whether there may not be more than a single species in our 
rivers; but to this for the present we hesitate to return a con- 
fident answer. Cuvier and Bloch are supposed to have made 
mistakes in this, and we prefer to follow the example of 
Willoughby and Sir William Jardine in considering the several 
appearances in which they differ as signs of variation only. In 
truth, we do not feel ourselves competent to decide at what 
point the line of distinction as regards species in this case should 
be drawn; since within the sphere of our own observation we 
have been witness to changes that have appeared to alter the 
identity of some varieties of this fish, while we have been 
confident of their being the same individuals; and we have 
known others that from apparently long-continued existence in 
one sort of form and colour, might be regarded distinct, but 
which under change of external circumstances have returned 
to a near resemblance of the usually common type. 
We take in the first place as our example the Common Trout 
of our rivers and brooks, the history of which is without 
obscurity, and by comparison with this the habits and forms of 
other and perhaps more doubtful kinds will be better understood. 
The Common Trout is a fish of much activity, and delights in 
clear and rapid streams, rvith a preference for such as flow over 
a clean and gravelly bottom. There it swims, usually and 
especially in cloudy and cold weather, low in the water where 
the river is not deep, and with its head against the current it 
maintains its station, perhaps near some eddy, with a watchful 
eye for every moving object. A worm or small shell-fish is 
acceptable, and it leaps eagerly at a fly that for a moment may 
stray or settle on the surface; but when larger grown it gives 
a preference to a small fish, and an unfortunate minnow, one of 
many in a sportive assemblage that are unconscious of fear or 
danger, is a temptation not to be resisted. It also watches the 
spawning of the Salmon to devour the roe in spite of the 
vigilance of the parents, and gorges itself with the helpless young 
ones as they show themselves above the gravel, within the shelter 
of which they had long lain hid ; but here, as with the imitated 
minnow, their eagerness leads them to their fate, for the angler 
supplies hin self with the coveted material as one of his most 
attractive baits. We have not thought it necessary to enter at 
