2. RADIATA.
The eastern seas are profusely stocked with radiated animals, but it is to be regretted that they have as yet received but little attention from English naturalists. Recently, however, Dr. Kelaart has devoted himself to the investigation of some of the Singhalese species, and has published his discoveries in the Journal of the Ceylon Branch of the Asiatic Society for 1856-8. Our information respecting the radiata on the confines of the island is, therefore, very scanty; with the exception of the genera[3951] examined by him. Hence the notice of this extensive class of animals must be limited to indicating a few of those which exhibit striking peculiarities, or which admit of the most common observation.
Star Fish.—Very large species of Ophiuridæ are to be met with at Trincomalie, crawling busily about, and insinuating their long serpentine arms into the irregularities and perforations in the rocks. To these they attach themselves with such a firm grasp, especially when they perceive that they have attracted attention, that it is almost impossible to procure unmutilated specimens without previously depriving them of life, or at least modifying their muscular tenacity. The upper surface is of a dark purple colour, and coarsely spined; the arms of the largest specimens are more than a foot in length, and very fragile.
The star fishes, with immovable rays[3961], are by no means rare; many kinds are brought up in the nets, or maybe extracted from the stomachs of the larger market fish. One very large species[3962], figured by Joinville in the manuscript volume in the library at the India House, is not uncommon; it has thick arms, from which and the disc numerous large fleshy cirrhi of a bright crimson colour project downwards, giving the creature a remarkable aspect. No description of it, so far as I am aware, has appeared in any systematic work on zoology.
Sea Slugs.—There are a few species of Holothuria, of which the trepang is the best known example. It is largely collected in the Gulf of Manaar, and dried in the sun to prepare it for export to China. A good description and figures of its varieties are still desiderata.
Parasitic Worms.—Of these entozoa, the Filaria medinensis, or Guinea-worm, which burrows in the cellular tissue under the skin, is well known in the north of the island, but rarely found in the damper districts of the south and west. In Ceylon, as elsewhere, the natives attribute its occurrence to drinking the waters of particular wells; but this belief is inconsistent with the fact that its lodgment in the human body is almost always effected just above the ankle. This shows that the minute parasites are transferred to the skin of the leg from the moist vegetation bordering the footpaths leading to wells. At this period the creatures are very small, and the process of insinuation is painless and imperceptible. It is only when they attain to considerable size, a foot or more in length, that the operation of extracting them is resorted to, when exercise may have given rise to inconvenience and inflammation.
These pests in all probability received their popular name of Guinea-worms, from the narrative of Bruno or Braun, a citizen and surgeon of Basle, who about the year 1611 made several voyages to that part of the African coast, and on his return published, amongst other things, an account of the local diseases.[3971] But Linschoten, the Dutch navigator, had previously observed the same worms at Ormus in 1584, and they are thus described, together with the method of removing them, in the English version of his voyage.
"There is in Ormus a sickenesse or common plague of wormes, which growe in their legges, it is thought that they proceede of the water that they drink. These wormes are like, unto lute strings, and about two or three fadomes longe, which they must plucke out and winde them aboute a straw or a feather, everie day some part thereof, so longe as they feele them creepe; and when they hold still, letting it rest in that sort till the next daye, they bind it fast and annoynt the hole, and the swelling from whence it commeth foorth, with fresh butter, and so in ten or twelve dayes, they winde them out without any let, in the meanetime they must sit still with their legges, for if it should breake, they should not, without great paine get it out of their legge, as I have seen some men doe." [3981]
The worm is of a whitish colour, sometimes inclining to brown. Its thickness is from a half to two-thirds of a line, and its length has sometimes reached to ten or twelve feet. Small specimens have been found beneath the tunica conjunctiva of the eye; and one species of the same genus of Nematoidea infests the cavity of the eye itself.[3982]
Planaria.—In the journal already mentioned, Dr. Kelaart has given descriptions of fifteen species of planaria, and four of a new genus, instituted 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.[3983]
Acalephæ.—Acalephæ[3984] 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 glassy, 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 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. 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.
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.