Part 45 (1/2)

_Planaria_.--In the journal already mentioned, Dr. Kelaart has given descriptions of fifteen species of planaria, and four of a new genus, inst.i.tuted by him for the reception of those differing from the normal kinds by some peculiarities which they exhibit in common. At Point Pedro, Mr. Edgar Layard met with one on the bark of trees, after heavy rain, which would appear to belong to the subgenus _geoplana_.[1]

[Footnote 1: ”A curious species, which is of a light brown above, white underneath; very broad and thin, and has a peculiarly shaped tail, half-moon-shaped in fact, like a grocer's cheese knife.”]

_Acalephae_.--Acalephae[1] are plentiful, so much so, indeed, that they occasionally tempt the larger cetacea into the Gulf of Manaar. In the calmer months of the year, when the sea is gla.s.sy, and for hours together 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 tentaculae; 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. The larger kinds, when undisturbed in their native haunts, 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.

[Footnote 1: Jelly-fish.]

[Ill.u.s.tration: PHYSALUS URTICULUS.]

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 gla.s.s 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 a.s.sumes a red tinge, considerably brighter than brick-dust; and this is confined to a s.p.a.ce 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 sh.o.r.e, and, on examination with the microscope, found it to be filled with _infusoria_, probably similar to those which have been noticed near the sh.o.r.es of South America, and whose abundance has imparted a name to the ”Vermilion Sea” off the coast of California.[1]

[Footnote 1: The late Dr. BUIST, of Bombay, in commenting on this statement, writes to the _Athenaeum_ that: ”The red colour with which the sea is tinged, round the sh.o.r.es 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.”]

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 h.o.r.n.y 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 paludinae, 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 gla.s.s 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.

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,

ROBERT E. GRANT.

_Sir J. Emerson Tennent, &c. &c._

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 l.u.s.tre, 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. l.u.s.trous 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. b.u.t.terflies 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 pa.s.sage--whence coming no one knows; whither going no one can tell.[1] As day declines, the moths issue from their retreats, the crickets add their shrill voices to swell the din; and when darkness descends, the eye is charmed with the millions of emerald lamps lighted up by the fire-flies amidst the surrounding gloom.