DISPERSION OF FRESH-WATER FISHES. 85 
down in its course, the Oatka falls over a ledge of 
rock, forming a considerable waterfall at Rock 
Glen. Still lower down its waters disappear in the 
ground, sinking into some limestone cavern or 
gravel-bed, from which they reappear, after some six 
miles, in the large springs at Caledonia. Either 
of these barriers might well discourage a quiet- 
loving fish; while the trout and its active associates 
have sometime passed them, else we should not 
find them in the upper waters in which they alone 
form the fish-fauna. This problem is a simple 
one; a boy could work it out, and the obvious 
solution seems to be satisfactory. 
Since those days I have been a fisherman in 
many waters, — not an angler exactly, but one who 
fishes for fish, and to whose net nothing large or 
small ever comes amiss; and wherever I go, I find 
cases like this. 
We do not know all the fishes of America yet, 
nor all those well that we know by sight; still this 
knowledge will come with time and patience, and 
to procure it is a comparatively easy task. It is 
also easy to ascertain the more common inhabi- 
tants of any given stream. It is difficult, however, 
to obtain negative results which are really results. 
You cannot often say that a species does not live 
in a certain stream. You can only affirm that you 
have not yet found it there, and you can rarely fish 
in any stream so long that you can find nothing 
that you have not taken before. Still more difficult 
is it to gather the results of scattered observations 
into general statements regarding the distribution 
of fishes. The facts may be so few as to be 
