OF FISHES. 47 



ORGANS OF SENSE. 



Hearing and seeing are probably tbe most per- 

 fectly developed of their senses. The machinery 

 of the internal ear is tolerably well understood, it 

 being satisfactorily ascertained that fishes are only 

 susceptible of simple sounds.* 



A DISSECTION OF THE EAR OF A HADDOCK, WHICH BEARS 

 A STRONG RESEMBLANCE TO THE LABYRINTH OF THE HU- 

 MAN EAR. 



C 



A. The sacculus vestibuli. 



B. The bony concretion which lies within, and which, by 

 its vibration, increases the impulse on the acoustic nerve. 



C The auditory nerve, passing to be distributed on the 

 sacculus vestibuli, and the extremities of the semicircular 

 canals. 



D D D. The semicircular canals, three in number, ar- 

 ranged very much as they are in quadrupeds. 



E. One of the extremities of the semicircular canals, in 

 which a twig of the auditory nerve is seen to be expanded. 



F. This is a smaller portion of the same nerve. 



* Fishes have no external ear, nor is there any visible open- 

 ing, except in the skate. But there have been so many 



