196 ON THE GROWTH OF 
Salmon-smolt and Sewin-smolt of six or seven inches 
in length, when none has been -lost, is ten, arranged 
in a row of five on each side; occasionally I have 
counted as many as twelve in both species, but ten 
appears to be the normal number. These teeth are 
not shed, but most of them are torn away by violence 
in an irregular manner as the fish advance in growth, 
so that a want of symmetry in the two rows is con- 
spicuous in much the greater number of individuals. 
I may remark that such is the case also in every par- 
ticular with the teeth on the tongue of the Common 
Trout (Salmo fario), and that the teeth on the vomer 
of this species are not shed, but, like those on the 
tongue and jaws, some of them are frequently removed 
in an irregular manner by violence. 
The teeth on the vomer of the Salmon-smolt and 
Sewin-smolt commonly exceed twenty (in numerous 
instances I have noticed twenty-four)—a fact which 
the minute inspection of the heads of both species, 
after having been placed in nests of the Great Wood- 
Ant (Formica rufa), and subjected to the anatomical 
process so admirably effected by that industrious in- 
sect, fully confirms. Unlike the teeth on the tongue, 
those on the vomer are shed gradually, commencing 
at the posterior part and disappearing in nearly 
regular succession as the fish increase in size; conse- 
quently the loss of teeth from the vomer, taken in 
conjur.ction with the form of the tail and the growth 
of these species, affords to experienced observers a 
