154 ANNALS NEW YORK ACADEMY OF SCIENCES 



Sorensen made his dissection on one specimen preserved in alcohol, con- 

 sequently the diagram is somewhat misleading, as can be seen by com- 

 paring it with the bladder and muscle taken from a fresh specimen (PI. VI. 

 fig. 1). Bridge uses this figure from Sorensen to verify the following state- 

 ment: "In other fishes, the air-bladder, without possessing special muscles 

 of its own, may, nevertheless, be partially invested by tendinous or partly 

 muscular and partly tendinous, extensions from the muscles of the body 

 wall." This muscle (m. sonificus) cannot be considered an extension of 

 the muscles of the body wall but a unique, specific muscle which has been 

 developed for the purpose of sound production. The muscles with the 

 aponeuroses are united with the swim-bladder by means only of a tendon 

 on the dorsal side immediately anterior to the base of the horns, and in 

 no way attach themselves directly to the bladder, which is completely sur- 

 rounded by the muscles and tendons. Sorensen states: "According to 

 its structure, the air-bladder of this fish must be a sound-producing organ. 

 Most probably the contractions of the muscles will, for a moment, compress 

 the air-bladder and strain its dorsal wall, each of which operations must 

 separately be able to bring the air-bladder to produce sound." Sorensen 

 did not make any physiological experiments and based his conclusions 

 entirely upon anatomical data. In the light of experiments soon to be 

 described it is evident that he did not understand the "drumming" mech- 

 anism. 



OtJier drumfishes examined. — Through the courtesy of Dr. Hugh M. 

 Smith (1905) of the Bureau of Fisheries, it has been possible for me to 

 examine specimens of the southern squeteague {Cynoscion nehuhsum, PI. 

 VI, fig. 2), the yellow-tail (Bairdiella chrysura, PI. VII, fig. 1), and the spot 

 (Leiostomus xanthurus, PL VII, fig. 2)} The anatomical relations of the air- 

 bladder and the m. sonijicus are so similar to those noted above that no 

 further description is necessary. In the spot the peritoneum is so pigmented 

 with black that the m. soiiificus is somewhat hidden. 



The Sea-Robin and the Toadfish. 



In these fishes there is found a swim-bladder which is so radically dif- 

 ferent in its outward appearances from that of the scitenoid fishes, and at 

 the same time is so characteristic, that attention is immediately attracted 

 to this organ. The sound produced, described as a grunt, differs markedly 

 in character from the drumming of the Scisenidie. 



1 These drawings were made from dissections completed by T. E. B. Pope of the Bureau 

 of Fisheries. 



