PISCES. 
181 
of the ova is not only invariably the same in individuals of what- 
ever size, but, as far as our experience reaches, is even often 
characteristic of the species of a genus. — We are unwilling to 
discuss the question whether such characters may have been 
gradually acquired by a species in the course of time ; but even 
assuming that this has been the case in the Wener Trout, there 
is not the slightest evidence to show that it is the descendant of 
the Salmon, and not of some other extinct Salmonoid. 
Further, how is it to be explained that those lakes, and a 
number of others, all over the northern hemisphere, are in- 
habited by that, we might say, fancifully distributed group of 
Salmonoids, the Charr, the origin of which cannot be deduced 
from a marine species ? How is it that the Truttse relictse 
are found in a number of lakes with broad outlets into the sea, 
some of which certainly existed from the first period of their 
separation from the salt water ? How is it that not one of the 
Truttcn relict(B has ever returned to the habits of its fore- 
fathers,^^ and descended to the sea, which became again, and 
now is accessible ? If a marine animal is gradually acclimatized 
in fresh water, it degenerates in size, but the lacustrine Salmon- 
oids of the different European lakes do not show themselves 
much inferior to the marine forms in this respect ; and where 
they have perceptibly diminished in size, as in the Lake of 
Geneva, this has been the case within a very late period, and is 
the consequence of an increased destruction of them by man. 
As regards the two lacustrine forms mentioned by Hr. 
Malmgren, the description of their characters is of the poorest 
kind. Important internal characters are not taken notice of at 
all; the difference in the size of the scales — one of the most 
constant and important characters in Salmonoids — is con- 
sidered of no value ; that of the size of the teeth is disposed 
of as being dependent on the food (all sportsmen will agree 
with him ) ! To have lumped together Salmo irutfa, S. ferox, 
S. lacustris from the Lake of Constance, S. microps, &c. as 
varieties of S. triitta, is a proof that the author has not entered 
very deeply into the subject ; we should go too far did we stop 
to point out here the distinctions, and may omit them, as the 
descriptions of these Salmonoids will form the subject of a sepa- 
rate publication. 
Finally, as regards Salmo fario^ we (and probably most ich- 
thyologists) have again the misfortune to entirely disagree with 
Messrs. Widegren and Malmgren, who regard it as a degenerate 
variety of the Sea-Trout. The reason they assign, that young 
and very old River-Trout cannot be distinguished from Sea- 
Trout of the same age, may lie in the individuality of the obser- 
ver. We confess to not having yet overcome the difficulties of 
distinguishing the different Sea-Trout {S. trutta, S. cambrictis, 
&c.) in the Parr-state; but a young River-Trout may always be 
