XXXVU1 HEARING. 



HEARING. 



Hearing is developed in all fishes (except perhaps in the Amphioxus), 

 and it is very remarkable how any diversity of opinion can exist asto their 

 possessing this sense. Mr. Bradley instances how at Rotterdam, seeing 

 some carps fed which were kept in a moat of considerable extent, and having 

 kept qniet some time in order to be convinced that the fish would not come 

 spontaneously, the owner called in the manner he usually did at feeding 

 time, when they immediately gathered from all parts of the moat in such 

 numbers that there was hardly room for them to lie by one another. The 

 same gentleman alludes to a pond full of tame pike at Sir J. Bowyer's, near 

 Uxbridge, which could be called together at pleasure. Lacepede relates 

 how some fish, which had been kept in the basin of the Tuileries for 

 upwards of a century, would come when they were called by their names ; 

 while in many parts of Germany, trout, carp, and tench were summoned to 

 their food by the ringing of a bell. At many temples in India fishes are 

 called to receive food by means of ringing bells or by musical sounds. 

 Lieutenant Conolly remarks upon seeing numerous fishes coming to the 

 ghaut at Sidhnath to be fed when called. Carew, in Cornwall, is said to 

 have called his grey mullet together by making a noise like chopping with 

 a cleaver, and Sir Joseph Banks collected his fish by means of sounding a 

 bell. Mr. Dunn remarks that he has known pilchards start out of the water 

 by tens of thousands on the Plymouth nine o'clock gun being fired, fully 

 thirty miles away. 



Irrespective of the fact of hearing comes the inquiry, why, if fish cannot 

 hear, do they possess a complicated internal auditory apparatus ? It is 

 generally asserted that in this class of animals there exists no vestige of an 

 external ear, but an auditory canal has been observed in some of the 

 Chondropterygians, as rays, opening on the surface of the head, near the 

 spiracle in dog-fishes, but in sharks it is generally covered by the skin. 



The internal auditory apparatus of fishes are, as a rule, placed outside 

 the cavity which contains the brain, as seen in sharks, or more or less 

 within the cranial cavity, as in teleosteans. Its chief constituent parts 

 are the labyrinth, which is composed of three semi-circular canals and a 

 vestibule, which latter expands into one or more sacs, where the ear-bones 

 or otoliths are lodged. A tympanum and tympanic cavity are absent. 



Many teleostean fishes possess fontanelles between the bones forming 

 the roof of the skull, and which, being closed by very thin bone or skin, 

 sounds from the surrounding water may be readily transmitted to the 

 contiguous internal ear. But the chief mode in which hearing exists must 

 be due to the surface of the fish being affected by vibrations of the water, 



