48 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
tank or concussions upon its walls. Lee, moreover, called attention to the fact that 
the papilla acustica basilaris, which is the special organ of hearing in the internal 
ears of the higher vertebrates, did not occur in the fishes. From the observations 
and experiments of Bateson and of Kreidl, and from his own work, Lee (1898, p. 138) 
believed that the conclusion was justified beyond doubt that fishes do not possess the 
power of hearing, in the sense in which the term is ordinarily used, and that the 
sole function of the ear in fishes is equilibration. 
The generalization to be drawn from the work just summarized, viz, that fishes 
do not hear, though they may respond to sound-waves by the skin, has seemed to 
me not wholly in accord with certain well-known facts in the natural history of these 
animals. Among these facts may be mentioned the undoubted ability on the part 
of some fishes to make sounds. If a fish has this power it might naturally be sup- 
posed to hear the sounds it makes. Lee (1898, p. 137) has called attention to the 
small number of sound-producing fishes as evidence against the view that fishes in 
general hear. But the fact that there are such fishes has always appealed to me 
in quite the reverse way and should, in my opinion, serve to indicate the species 
most worthy of attention in any investigation of the sense of hearing. It must be 
admitted, however, that fishes may possibly produce sounds that they themselves can 
not hear, but that other animals may hear and take warning from. Thus when small 
swell-fish, Chilomycterus scJiiepji, are thrown into a tank containing hungry scup, 
Stenotomus chrysops , they are immediately, set upon by the latter. In defense the 
swell-fishes inflate themselves with sea water till their tegmentary spines stand out 
rigidly, and at the same time they make a peculiar sound by gritting the two front 
teeth of the lower jaw against the inner surface of those of the upper jaw. It is not 
known that this sound is heard by the swell-fish, though it may be. All that one can 
say with certainty is that the sound seems to be directed against the foe, for it is 
made, so far as I know, only when the swell-fish is molested. Granting, however, 
that the swell-fisli does not hear its own sound, one would still be rash to conclude 
that this was an argument against the hearing of fishes, for the vast majority of 
animals toward which the sound is directed are fishes themselves, and these pre- 
sumably hear the sounds. 
Another good instance of the production of sound by a fish is found in the 
squeteague or weak-fish, Cynoscion regalis. The grunting noise made by this fish is, 
however, produced only by the males, and this specialization is very difficult to under- 
stand unless one assumes an ability on the part of one or other sex to hear. Since 
the sounds made by both the swell-fish and the squeteague are in no sense shocks or 
concussions but resemble more closely, in rate of vibration and in intensity, such 
sounds as might be obtained from the ordinary action of an instrument like a tuning- 
fork of low pitch, it seems to me that they afford evidence in favor of the sense of 
hearing rather than the reverse. 
A second reason for questioning the generalization advocated by Kreidl, and 
by Lee, is the character of the observations upon which it is based. Both authors 
state that no positive evidence in favor of hearing could be obtained. But it must 
be borne in mind that in many animals known to possess a sense of hearing the 
auditory reflexes are perhaps the least conspicuous of any connected Avith the more 
important sense organs, and that consequently the most careful scrutiny of the 
movements of fishes must be made before one can with certainty declare that hear- 
ing is absent. A perusal of the papers already summarized led me to the conclusion 
