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BULLETIN OF THE UNITED STATES FISH COMMISSION. 63 
19.— CKOAK5PTC} OF THE PERCH. 
By 'W. R. HAMILTON, M. B, 
j My observations with regard to the croaking or grunting noise made 
by the Drumfish family have been confined to the fish known here as the 
« Perch ” ( Haploidonotus grunniens). This fish, as is well known, is fur- 
nished with a masticatory apparatus in the gullet, and the lower division 
of this has its upper surface flat and triangular* in outline, and studded 
all over with spheroidal “teeth,” if they may be called genuine teeth. 
IThe upper division is composed of two parts united by a ligament; their 
lower surfaces are also supplied with similar teeth. The divisions of this 
i apparatus have powerful muscles attached to them by which they can be 
pressed together and moved laterally on each other. By this process 
the fish masticates the crustaceans on which it feeds. When this action 
takes place, the teeth coming in contact and gliding over each other 
produces the croaking of the perch. 
About twenty years ago, for the purpose of endeavoring to ascertain 
by what means the croaking of the perch was produced, I procured 
from an Ohio River fisherman a perch weighing 18J pounds, which he 
declared was the largest perch he had ever caught. I divided the head 
on one side, and thus exposed its masticatory apparatus; and while 
moving its grinders as I supposed the fish had done during life when 
crushing a crawfish, an exact imitation of the croaking of the perch was 
produced. I produced the sounds in a similar manner within the hear- 
ing of several Allegheny River raftsmen and Ohio River fishermen at 
intervals during the day on which I experimented, without allowing 
them to know how the noises were made, or that a perch was used for 
the purpose, and they all declared that it was an exact imitation of the 
croaking of the perch. This noise is made, I believe, only at the season 
of the year when the perch “bites” or feeds. The above experiment 
and others of a similar kind lead me to believe firmly that the croaking 
of the perch is produced in the manner referred to. I cannot conceive 
of any way by which the sound could be produced by the air-bladder 
of the fish, as its physiological functions and anatomical structure do 
not indicate its use as a vocal organ * 
Pittsburgh, Pa., April 30, 1887. 
* Prof. John A. Ryder, in a letter commenting on the above, May 21, 1887, said: 
“ It is now known that certain sound-producing fishes give out noises by grating cer- 
tain hones together in a peculiar way. An extensive memoir by a Danish author has 
appeared within two years, the Danish title of which has escaped me, but which 
deals with this question at great length, with fine illustrations. The usual view, 
that the air is forced from one part of the air-bladder to another in the Scimnoids, 
seems to me inadequate in the absence of clearly worked-out demonstrations. This 
group is physoclystous, or has the air-bladdey entirely closed.” 
