304 SUPPLEMENT ON 



sides. In proportion as they went up the river the sounds 

 diminished, and finally ceased altogether. The interpreter 

 told Captain White that they were produced by a troop of 

 fishes of an oval and flatted form, which have the faculty of 

 strongly adhering to divers bodies by the mouth. 



M. Humboldt was witness to a similar fact in the South 

 Sea, but without suspecting the cause. On the 20th of Fe- 

 bruary, 1803, towards seven in the evening, the whole crew 

 were astounded by an extraordinary noise, which resembled 

 that of drums which were beating in the air. It was at first 

 attributed to the breakers. Speedily it was heard in the 

 vessel, and especially towards the poop. It was like a boil- 

 ing, the noise of the air which escapes from fluid in a state 

 of ebullition. They began then to fear that there might be 

 some leak in the vessel. It was heard unceasingly in all 

 parts of the vessel, and finally, about nine o'clock, it ceased 

 altogether. From the narrations from which we have now 

 extracted, and from what so many observers have reported 

 touching various sciaenoides, we may believe that it was also 

 a troop of some of their species which occasioned the noise 

 in question. 



It would be an object of curious research to find out the 

 organs in these fishes which seem to produce such strong and 

 such continuous sounds, and that at the bottom of the water, 

 and without any communication with the external air. Most 

 of the sciaenoides have large natatory bladders, very thick, 

 provided with very strong muscles, and which in many 

 species have prominences or productions more or less com- 

 plicated, which penetrate even into the intervals of the ribs. 

 This may direct the attention of physiologists to this point, 

 but at the same time it must be observed, that these bladders 

 have no communication either with the intestinal canal, or 

 with the exterior generally. 



The drums, according to Dr. Mitchill, swim in numerous 



