202 ON THE GROWTH OF 
ascertained also, by the dissection of very numerous 
specimens, that the males of the Salmon and Sewin 
shed their milt before they make their first descent 
to the sea, but that the females do not spawn till they 
return from their first visit to the salt water; indeed 
the ova are so little developed in the month of May, 
at which time the principal migration seaward takes 
place, as scarcely to be discerned without the aid of 
a magnifier. 
Perhaps no appellation employed by ichthyologists 
to designate any of the various stages of growth 
through which the Salmon passes has been more 
abused or has led to greater confusion and misappre- 
hension than the Scotch term Grilse, which is applied 
to fish of this species supposed to have returned from 
the sea for the first time and not to have spawned ; 
but as male Salmon-smolts are known to have milted 
before they descend to the sea, it is plain from this 
fact, independently of others, that the term ought to 
be rejected. 
Among the external characters which serve to di- 
stinguish the Sewin-smolt from the Salmon-smolt 
are:—a more robust and trout-like figure, a more 
decided prominence of the row of scales forming the 
lateral line, a greater number of spots below that line, 
a yellowish tinge on the lighter-coloured pectoral fins, 
a bright-red tint at the extremity of the adipose fin, 
and a firmer adhesion of the scales to the skin. 
In conclusion, I shall briefly notice a few cases of 
