67 



SECTION VIII. 



Organs of Hearing in Fishes. 



THE organ of hearing in fishes consists of little 

 more than the labyrinth, and that a much less 

 complicated one than the corresponding part in 

 either quadrupeds or birds. They have no external 

 ear, unless we may bestow that name on a small 

 cavity, sometimes slightly spiral, which we find in 

 skates. It is, however, always covered by the 

 skin, and is not perceptible among the osseous 

 fishes. Those anatomists who find in the opercular 

 bones the four bones of the ear of man, suddenly 

 and prodigiously developed, hazard such a notion 

 merely on the assumption that the bony pieces are 

 the same in number in all crania ; but it must be 

 borne in mind that neither the form, relations, nor 

 functions of these bones, nor their nerves and 

 muscles, support such a comparison. The ear of 

 fishes is in truth much less complete than in quad- 

 rupeds or birds, or even in the majority of reptiles. 

 There is no doubt that they possess the power of 

 hearing, though merely as a general sense of sound, 

 and in all probability without the power of per- 

 ceiving any variety or range of intonation. " The 

 sense of hearing," says Mr. Yarrell, " has by some 

 been denied to fishes, perhaps because they exhibit 

 no external sign of ears : the internal structure, 

 however, may be most successfully demonstrated in 

 the various species of skate, in which the firmer 



