THE SALMON AND SEWIN. 195 
observed to select for the purpose, and by exhibiting 
them alone when recaptured, or by adapting the 
marks to fish subsequently taken, whose dimensions 
appear to be best suited to promote the end they have 
in view. Besides, it often happens that all the par- 
ticulars of the undertaking transpire, and, becoming 
widely circulated, other parties resident in the neigh- 
bourhood may apply similar marks to fish of different 
sizes captured in the same stream, more especially to 
kelts, which are comparatively of little value; and 
that this is not merely a supposititious case, or an 
imaginary cause of delusion, I can confidently affirm 
from personal experience. Perforations, and the 
total or partial excision of any of the fins, may be 
objected to on account of the modifications which 
such marks undergo with the growth of the fish, and 
also on account of the mutilations to which those 
members are liable from incidental circumstances. 
Having thus succinctly directed attention to a few 
of the objections which may be urged against the 
manner in which attempts to ascertain the rate of 
growth in fish by employing artificial marks are 
generally conducted, I shall revert to the method 
pursued in my own researches—namely, careful and 
frequently repeated observations on the gradual loss 
of the teeth from the vomer, on the order in which 
they are shed, and on the changes known to take 
place in the figure of the caudal fin. 
The usual number of teeth on the tongue of the 
02 
