480 THE NORTHEEN FORESTS. [Pakt IX. 



NOTE. 



TRITONIA ARBOEESCENS. 



The following is the letter of Dr. Grant, referred to at 

 page 471 : — 



Sir, — I have perused with much interest, your remarkable 

 communication received yesterday, respecting the musical sounds 

 which you heard proceeding from under water, on the east 

 coast of Ceylon. I cannot parallel the phenomenon you witnessed 

 at Batticaloa, as produced by marine animals, with anything 

 with which my past experience has made me acquainted in 

 marine zoology. Excepting the faint clink of the TrUonia arbo- 

 rescens, repeated only once every minute or two, and apparently 

 produced by the mouth armed with two dense horny laminae, I 

 am not aware of any sounds produced in the sea by branchiated 

 invertebrata. It is to be regretted that in the memorandum you 

 have not mentioned your observations on the living specimens 

 brought you by the sailors as the animals which produced the 

 sounds. Your authentication of the hitherto unknown fact, 

 would probably lead to the discovery of the same phenomenon 

 in other common accessible paludinse, and other allied branch- 

 iated animals, and to the solution of a problem, which is still to 

 me a mystery, even regarding the tritonia. 



My two living tritonia, contained in a large clear colourless 

 glass cylinder, filled with pure sea water, and placed on the 

 central table of the Wernerian Natural History Society of 

 Edinburgh, around which many members were sitting, con- 

 tinued to clink audibly within the distance of twelve feet 

 during the whole meeting. These small animals were individu- 

 ally not half the size of the last joint of my little finger. What 

 effect the mellow sounds of millions of these, covering the 

 shallow bottom of a tranquil estuary, in the silence of night, 

 might produce, I can scarcely conjecture. 



In the absence of yoiu' authentication, and of all geological 



