162 Traces of a Voice in Fishes. [ March, 
conclude that his sole dependence in securing a mate is in his 
brilliant coloring. 
What a contrast is presented in the lazy, dull-colored cat-fish 
that slowly wanders over the muddy bed of the stream, if per- 
chance he is moving about at all, during the day! Not a motion 
can be detected that is not referable, without doubt, to so 
prosaic a matter as the search for food. If a dozen or more 
come together, it is but to hunt in concert, and nothing of the 
nature of a contest is to be seen. But after sunset, every one 
of their kind becomes suddenly more animated; there is a 
marked restlessness in their every movement, as they congregate 
in large numbers in some limited area. At such a time, their 
presence is to be detected not only by the aid of “submarine 
lanterns ” and all the troublesome helps that one must employ 
to study fishes at night; there is an opportunity given to use 
one’s ears as well as eyes, and by careful, patient waiting we 
may hear, even from the deeper waters, a gentle humming sound 
that, if noticed at all, by most people would be referred to the 
insect life teeming about them. If, knowing or suspecting the 
true origin of this gentle murmur, we can, without alarming the 
fish, float our boat carefully to a point directly above them, we 
will find that scores of chains of little air bubbles are rising tO 
the surface ; and as the sound increases or dies away, in propor- 
tion to the abundance or absence of the bubbles, it is safe to 
refer the sound to the fishes that by voluntarily expelling the air 
from their bodies produce the murmurs we have mentioned. 
But, thanks to the aquarium, by its aid we have confirmed it. 
I have not the space, here, to enumerate all the circumstances 
connected with these voluntary emissions of sounds by certain 
of our fishes, seven species of which I have particularly men- 
tioned. Brief references to the others must here suffice. Con- 
cerning the first mentioned of our little list, the spineless perch, 
or “pirate” (Aphrodederus sayanus) : my knowledge of its 
habits have been mostly derived from aquarial studies, but al- 
though the diminutive size of the very largest specimens ob- 
tained —-a little over four inches in length — rendered it very 
difficult to be certain that sound accompanied the expulsion a 
air from their bodies, I am almost sure I detected it, and the 
actions generally of the fish were such as to render it in a high 
degreé probable that there was a sound heard by the female — | 
fishes of their kind. a o 
Of the percoid, that I have here called the “mud sunfish” 
