- TENTH ANNUAL MEETING. - 65 
FISHES WHICH CAN LIVE IN BOTH SALT AND FRESH 
WATER. 
BY FRED. MATHER, 
In respect to the medium which they inhabit fishes may be di- 
vided into three classes, viz.: salt water fishes, fresh water fishes, 
and a third class which can live in either fresh or salt water in- 
differently. There is no name for this class, that I can learn, and, 
if there is no objection, I will propose to call them Amphiectous 
fishes, from the Greek Amphz, both or everywhere, and Ozkeo to 
inhabit. This class includes many fishes besides the anadro- 
mous fishes which leave the sea and seek the rivers to spawn, 
and the catadromous fishes which leave the fresh to spawn in 
salt or brackish waters, as the eel does. It contains fishes which 
seem to be indifferent to the medium which they breathe so far 
as its saltness or freshness is concerned, provided the change is 
not made too suddenly, and it is an open question if the chemical 
properties of salt water are of as much importance to the fishes 
living in it as its destiny is, but it is one that I have no inclina- 
tion at present to discuss. ie 
Foremost among the fishes which seem at home, as far as 
breathing and procuring food are concerned, in either salt or 
fresh water, are most members of the salmon family, I say most 
members because there are some which do not seem to have been 
observed in salt water, but as I think it highly probable that all 
members of this family, which as at present constituted includes 
the salmons, trouts, smelts and the coregont or ‘““whitefishes,” 
“Jake-herrings,” graylings, ciscoes, etc., are descended from a 
common ancestor and have been differentiated by physical causes, 
there would seem reason to suppose that the graylings and other 
untried members might live in salt water also. These fishes 
may not be able to increase their species without access to fresh 
waters, as the density of salt water is probably too great for the 
gills of the embryo, even if it did not destroy the embryo before 
its gills were formed. In some experiments which I made a few 
years ago with young quinnat salmon of six months old, it was 
found that when placed in sea water they showed signs of uneasi- 
