146 HEARING OF FISHES. 



" have been known to anatomists for more than 

 two hundred years. They are especially con- 

 structed for receiving sounds in water, and for 

 repeating those limited vibrations which pass 

 through water ; while the organs of hearing in 

 animals, which live in air, are adapted to that 

 medium ; and those of amphibious creatures, are 

 fitted for both elements. Insects appear to feel 

 the vibratory motions termed sounds, with the 

 instruments called antenna3 or horns. Sounds are 

 only modifications of vibratory motions, but these 

 are liable to unlimited variations, as exemplified 

 by music. 



" The organs of hearing are in all creatures 

 ordained to afford them information respecting 

 the movements of distant objects, but those per- 

 ceptions (as well as the sense of seeing) are with- 

 held from stationary beings, such as trees, be- 

 cause the evidences of hearing and seeing are 

 only serviceable to moving or roving creatures. 



" The mechanical structure of the organs of 

 hearing in fishes is more simple than in aerial 

 animals. The sounds which especially affect the 

 welfare of fishes, are those which occur in their 

 own element, such as the rushings or concussions 

 of waters, the attrition of stones or sand, or the 

 movement of aquatic creatures, whether their 

 natural enemies, or their prey. For these essen- 

 tial purposes, the ears of fishes are repeaters of 



