SENSES HEARING. 201 



quiring mutual impregnation, the sounds may possibly be a 

 means of communication between them ; or, if they be of an 

 electric nature, they may be a means of defending from 

 foreign enemies one of the most delicate, defenceless, and 

 beautiful Gasteropods that inhabit the deep." * 



You must not confound these sounds of the Tritonia and 

 Eolis with what has been absurdly called the " music of 

 snails," a noise created by the crawling of them on a moist 

 window-pane of glass, f This is mechanical, and has no 

 connection with the animal. As the source of the noise is 

 often unsuspected, and as it is heard only in the evening 

 after the dew has fallen, or at the witching hour of night, it 

 has caused on some occasions a superstitious dread, and has 

 afforded the ingenious Mrs. Bowdich a foundation for an 

 interesting tale. 



* Edinb. Phil. Journ. xiv. 186. f Mag. Nat. Hist. n. s. i. 107. 



