Occasionally after storms, the beach at Colombo is strewn with the thin transparent globes of the "Portuguese Man of War," Physalus urticulus, which are piled upon the lines left by the waves, like globules of glass delicately tinted with purple and blue. They sting, as their trivial name indicates, like a nettle when incautiously touched.
Red infusoria.—On both sides of the island (but most frequently on the west), during the south-west monsoon, a broad expanse of the sea assumes a red tinge, considerably brighter than brick-dust; and this is confined to a space so distinct that a line seems to separate it from the green water which flows on either side. Observing at Colombo that the whole area so tinged changed its position without parting with any portion of its colouring, I had some of the water brought on shore, and, on examination with the microscope, found it to be filled with infusoria, probably similar to those which have been noticed near the shores of South America, and whose abundance has imparted a name to the "Vermilion Sea" off the coast of California.[4001]
The remaining orders, including the corals, madrepores, and other polypi, have yet to find a naturalist to undertake their investigation, but in all probability the new species are not very numerous.
NOTE.
TRITONIA ARBORESCENS.
The following is the letter of Dr. Grant, referred to at page 385:—
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 Tritonia arborescens, repeated only once every minute or two, and apparently produced by the mouth armed with two dense horny laminæ, 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 paludinæ, and other allied branchiated 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, continued to clink audibly within the distance of twelve feet during the whole meeting. These small animals were individually 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.