VOICE. XXXIX 



caused by sounds transmitted directly to the internal ear, or else by means 

 of the air-bladder acting as a sounding-board (see page xliii). 



Prior to observing upon the air-bladder arises the question, whether fish 

 can or cannot communicate- by means of sound one with another. Mr. 

 Symonds tells us how, introducing a brass minnow as a bait he killed a 

 large number of perch in four days in a certain piece of water, but that 

 subsequently they entirely refused this bait, although, on the pond being 

 drained, thousands of these fish were found to be present. Also that he 

 has seen the same result follow in another piece of water, whereas in 

 neither could one in a hundred fish have been pricked by the hook. 



* 



VOICE. 



Voluntary and -involuntary sounds, due to emotions, ai'e emitted in 

 different manners by many fishes, and in some rare instances solely at 

 certain seasons. Very dissimilar organs may originate somewhat similar 

 sounds, while sounds apparently identical may not always be expressive of 

 the same feeling. But as the human voice can be modified into tones of 

 command, love," terror, &c, so in fishes one sound may denote fear, danger, 

 or anger, and perhaps even terms of conjugal endearment. 



M. Dufosse conducted with great care experiments on these subjects 

 upon some of the fishes of the Mediterranean, and reduced his results to a 

 system, in which the various sounds and modes of their production are 

 most elaborately classified. Thus some occur on their being removed from 

 hooks and thrown into a bucket ; these may be temporary and mostly 

 involuntary, and often convulsive and unintentional : their production may 

 be due to unusual movements of the jaws, opercles, or other bony elements; 

 or else induced in thick-lipped forms, as the. tench and carp, when com- 

 pelled to suddenly open their mouths ; the tench repeats the noise from its 

 lips so frequently that it has been compared to the croaking of a frog. 



There are voluntary sounds as constant ones always produced by the 

 same organ which are evidently intentional, and can even serve to characterize 

 a species. Thus we find expressive sounds as of a harsh grating nature, as 

 stridulation caused by the friction of the dental organ, or of some bones as 

 the pharyngeals which guard the entrance into the gullet, or the densely 

 hard pi'ominences of the jaws as observed in the sun-fish. Musical sounds 

 may be occasioned by the contraction of muscles which are contiguous to 

 the air-bladder, or are attached to the air-bladder itself as in the " mailed 

 gurnard." 



Many fishes when captured emit sounds which appear to be due to terror, 

 as a scad or horse-mackerel (0 'ar una; hippos) ; a globe-fish (Tetrodon), and 

 others grunt like a pig. A Siluroid found in the Rio Parana, and called the 



