3IO SCHARFF : ORGANS OF SENSE IN MOLLUSCA. 



It nov; remains to say a few words about the physiological 

 function of the organ of hearing. The only result of the numer- 

 ous experiments which have been made, chiefly by Moquin- 

 Tandon, to test the capacity of the auditory organ, has been to 

 prove the superiority of the Lamellibranch ear over that of the 

 Pulmonates. The anatomical arrangement seems also in favour 

 of this view. Such a structure as the spongy capsule of Anodon, 

 for instance, would provide a very elastic suspension for the 

 otocyst. The transmission of the sound-waves would conse- 

 quently take place in a more uniform manner and render the 

 ear more sensitive. 



What idea should we form as to the perceptive powers of 

 this so-called ear ? Is the mollusc able to distinguish sounds 

 or merely concussions, in order to beware of danger ? The 

 answer to these questions is not easily demonstrated by experi- 

 ment, but according to several authors it would appear that 

 many snails can emit sounds. As these sounds are no doubt 

 in many cases meant to attract other snails, we come to the 

 natural conclusion that they have the faculty of distinguishing 

 sounds. 



Lieut-Col. Portlock read a short note at the Eighteenth 

 Meeting of the British Association, on this subject. He stated 

 that Helix aperta, which abounds at Corfu, was remarkable for 

 its property of emitting, when irritated, a strong and well-marked 

 sound. The sound is distinctly audible and possesses a singular 

 grumbling or querulous tone. 



A more remarkable statement was made by T. L. Taylor, 

 at the same meeting, on the so-called singing shells of Ceylon. 

 It would appear that at night a loud musical noise is heard on 

 the shore, proceeding from the bottom of the water, and caused 

 by these shells. The sounds are said to be like those of an 

 accordion or seolian harp, pitched in different keys. 



Although these reports seem to strengthen the belief in the 

 existence of high perceptive powers in the ear of some snails, 

 no apparatus like that existing in many insects (Orthoptera), by 



J.C, iv., April, 1S85. 



