NATURAL HISTORY OF BRITISH SALMONIDA. 143 
a great desire to escape observation—an instinct given to them, 
no doubt, for their preservation during so feeble and helpless a 
condition. On the disappearance, however, of the yolk bag 
and assurnption of the parr marks, they come from their hiding 
places, and are to be found, on careful search, in the streams 
in or near which the parent salmon deposited their spawn 
during the preceding winter. 
- At two months old the parr begins to acquire a more 
symmetrical form, and’ the disproportion in the size of the 
head ceases to be observable; at four months the characteristic 
parr marks are clearly defined ; and at six months the fry has 
reached the length of three or four inches, and is the small- 
sized parr so constantly found in salmon rivers. 
The next change is that of the parr into the smolt, prepa- 
ratory to the first migration to the sea. 
In somewhat more than twelve months from the time of 
hatching, that is, between the middle of April and the early 
part of June—about half of the last year’s parr begin to assume 
their ‘bathing dress’ or coating of silver scales as contrasted 
with the yellower scales worn up to this period. These silvery 
scales, which form the distinctive mark of the smolt, as dis- 
tinguished from the parr, are never put on except when the 
fish is about to migrate ; and without them it will not migrate 
at all, and cannot exist in salt water, as has been proved by 
experiment. These scales come off upon slight pressure and 
the parr marks are visible below. 
At this time the habits of the transforming fish undergo a 
marked alteration. As parr they show no disposition to con- 
gregate, each occupying its own place in the pond, and any 
intruder upon a post already tenanted being instantly and 
forcibly expelled ; but as soon as the whole brood have donned 
their travelling costume—an operation usually lasting two or 
three weeks—they collect in a shoal, and show their desire to 
escape by scouring about hither and thither, leaping and sport- 
ing, and generally displaying a greatly increased amount of 
energy and activity. 
