150 Traces of a Voice in Fishes. [ March, 
corporalis) will doubtless urge as an exception, that the peculiar 
grunting sounds made by this fish when taken from the water 
entitle it to a place among the list of species supposed to have a 
voice; but I have not been able to detect this sound except at 
such a time, and as the fish is then out of water and struggling, 
it may be involuntary. On the other hand the deep bronze and 
golden-green tints of the fresh-water bass, or ‘‘mud sunfish” 
(Acantharcus pomotis), may be maintained to be a case of high 
coloration, and a sexual attraction ; and the same miglit be said 
of the land-locked gizzard shad (Dorosoma cepedianum), but the 
former of these has been most frequently of all fishes observed 
by me to voluntarily utter sounds when confined in an aqua- 
rium; still I doubt not there are many exceptions, and one great 
objection, and at first it seems a fatal one, to the suggestions I 
have made is that there probably are so very many exceptions 
to the supposed rule. But to refer again to the case of birds. 
Assuming the correctness of evolution, as I do, then we need go 
back but a very short period in geological time to see the numer- 
ous species of our birds reduced to single representatives of each 
genus, and even far fewer of so-called genera. With the avifauna 
thus simplified, the differences that now exist between our som- 
bre-hued songsters and gayly colored songless birds, were doubt- 
less more marked ; and might not this be held true of our fishes 
also? The vast influence brought to bear upon all animals 
by their surroundings and the increasing struggle for existence 
has evolved in later times and is evolving innumerable vari- 
ations in the forms of life of the present time; and these changes 
have in so great a measure obscured the conditions that once 
characterized both our birds and fishes, in the matter of the re- 
lationship of voice and color, that what I believe to have been 
once a well-marked feature of animal life is now traced with 
difficulty. Nevertheless, the many instances of apparent voice 
that I have noticed, and their relationship as to color, induce me _ 
to believe that what is now scarcely a rule, perhaps, as obtaining 
among fishes, was once a law that governed them. 
In studying these same fishes in another phase of their habits, 
we see that while all of the species enumerated are active through- 
out the day, it cannot be questioned that some of them are far 
more active at night, and shun, if undisturbed, the glare of mid- 
day sunshine. These partially, if not strictly nocturnal species 
are those that I have considered as having the power to give 
out or utter a truly vocal sound, and they are the more plainly 
