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undisturbed by a ripple, the minute descriptions are rendered perceptible by their beautiful prismatic tinting. So great is their transparency that they are only to be distinguished from the water by the return to the eye of the reflected light that glances from their delicate and polished surfaces. Less frequently they are traced by the faint hues of their tiny peduncles, arms, or tentaculæ; and it has been well observed that they often give the seas in which they abound the appearance of being crowded with flakes of half-melted snow. larger kinds, when undisturbed in their native haunts,

The

PHYSALUS URTICULUS,

attain to considerable size. A faintly blue medusa,

nearly a foot across, may be seen in the Gulf of Manaar, where, no doubt, others of still larger growth are to be found.

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.1

The remaining orders, including the corals, madre

The late Dr. BUIST, of Bombay, in commenting on this statement, writes to the Athenæum that: "The red colour with which the sea is tinged, round the shores of Ceylon, during a part of the S.W. monsoon is due to the Proto-coccus nivalis, or the Himatta-coccus, which presents different colours at different periods of the year—

giving us the seas of milk as well as those of blood. The coloured water at times is to be seen all along the coast north to Kurrachee, and far out, and of a much more intense tint in the Arabian Sea. The frequency of its appearance in the Red Sea has conferred on it its name."

pores, 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, con

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tinued 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.

In the absence of your authentication, and of all geological explanation of the continuous sounds, and of all source of fallacy from the hum and buzz of living creatures in the air or on the land, or swimming on the waters, I must say that I should be inclined to seek for the source of sounds so audible as those you describe rather among the pulmonated vertebrata, which swarm in the depths of these seas-as fishes, serpents (of which my friend Dr. Cantor has described about twelve species he found in the Bay of Bengal), turtles, palmated birds, pinnipedous and cetaceous mammalia, &c.

The publication of your memorandum in its present form, though not quite satisfactory, will, I think, be eminently calculated to excite useful inquiry into a neglected and curious part of the economy of nature.

I remain, Sir,

Yours most respectfully,

Sir J. Emerson Tennent, &c. &c.

ROBERT E. GRANT.

403

CHAP. XII.

INSECTS.

OWING to the favourable combination of heat, moisture, and vegetation, the myriads of insects in Ceylon form one of the characteristic features of the island. In the solitude of the forests there is a perpetual music from their soothing and melodious hum, which frequently swells to a startling sound as the cicada trills his sonorous drum on the sunny bark of some tall tree. At morning the dew hangs in diamond drops on the threads and gossamer which the spiders suspend across every pathway; and above the pool dragon-flies, of more than metallic lustre, flash in the early sunbeams. The earth teems with countless ants, which emerge from beneath its surface, or make their devious highways to ascend to their nests in the trees. Lustrous beetles, with their golden elytra, bask on the leaves, whilst minuter species dash through the air in circles, which the ear can follow by the booming of their tiny wings. Butterflies of large size and gorgeous colouring, flutter over the endless expanse of flowers, and at times the extraordinary sight presents itself of flights of these delicate creatures, generally of a white or pale yellow hue, apparently miles in breadth, and of such prodigious extension as to occupy hours, and even days, uninterruptedly in their passage whence coming no one

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