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FORMATION OF ATOLLS. 259
building corals have continually risen higher and higher, so as to remain in the shallow water, in which alone they can live, and thus in course of ages the condition of things becomes reversed. The once fertile isle disappears beneath the ocean, whereas the coral-reef, rising to just below high-water mark, gradually accumulates shells and sea-weeds; the sea deposits drift of all sorts, and, little by little, a soil is formed which becomes fertile, and presently cocoa-nuts drift from far-away isles, and weeds of many sorts are carried by the birds, or float on the currents, and so the isle becomes fertile—a ring instinct with life, rising perpendicularly from the deep sea on the outer side, and very often on the inner side also.
Where this is the case, and the inner lagoon appears as fathomless as the outer sea, it is supposed that the atoll has been formed on the rim of a sunken crater, colonies of living corals having settled on its surface so soon as it subsided below high-water mark. This theory seems the more probable, from the manner in which you find these circular coral-isles densely clustered in certain localities, and none in other groups, just as in some regions wo find innumerable extinct craters covering the whole surface of the land, and can readily imagine that should such a district subside, each cup-like crater might soon be covered with corals.
As in some craters the lava-flow has rent a gap near the summit whereby to escape, and in other craters it has found for itself a subterranean passage, leaving the upper crust unbroken, so in these atolls, some are perfect rings, and the tides ebb and flow within the lagoons by submarine channels, while others have an open passage, deep enough for a ship to sail into the inner lake.
The principal island in the Paumotu group is that of Manga Reva, a cluster of five isles, all within one encircling reef. The main isle is a basaltic mass, rising 2000 feet above the sea-level. It is the most fertile of the group, and is the headquarters of the French bishop and his clergy. The Paumotus have a population of about 5000 persons, the majority of whom are Roman Catholics. They are a fine independent race, and in old days were accounted brave warriors.
Now a large number make their living by diving for the great pearl shell-oysters, which are found in many of the lagoons at a depth of from ten to twenty fathoms, attached to the coral-rock by a strong byssus—1'.&, a bunch of silky golden-brown filaments, which the diver cuts with his knife, and so secures his prize. This silken cable is attached to the muscle of the fish itself, and passes through an aperture at the hinge. An expert diver can remain under water for about three minutes. In some of the isles women are accounted the most skilful divers, especially in deep water, where the largest shells are found, some actually measuring eighteen inches across—such beautiful great shields of gleaming mother-of-pearl.
The pearls themselves are not very abundant, and are generally found in the less perfect shells, the inmates of which are either sickly or have inadvertently admitted grains of coral-sand, which they have been unable to eject . But sometimes the large healthy shells contain one beautiful perfect pearl, not lodged in the musck in the ordinary way, but lying loose in the shelj; and though it is, certain that many are lost through carelessness, a considerable number have taken high rank among the noted pearls of the civilised world. I believe that those composing the Empress Eugenie's splendid necklace were collected in the Paumotus, and that Queen Victoria's pearl, which is valued at £6000, was also found there. In heathen days all the best pearls were treasured in the idol temples, and some of the early adventurers arc known to have made a very lucrative business by exchanging cheap muskets for bags of pearls. The same disease or discomfort which produces these lovely gems often takes a form less valued, but still very beautiful—large distorted pearly lumps, often the size of two joints of the little finger, and assuming all manner of quaint forms, sometimes resembling a human hand. I have seen some which had been set as pins and brooches, which I thought very attractive.
These, however, like the pearls themselves, are the accidental prizes of the divers. The regular article of traffic is the- shell itself, which the traders buy from the natives at an average of £l> per ton, and sell in London at an average of over £100. They
calculate that by hiring divers and working the beds themselves, the shell can be raised at less than £6 per ton. In former years the annual harvest of Paumotu pearl-shell was immensely in excess of the present supply, which is said not to average above 200 tons —the natural result of allowing the beds no time to recruit. Doubtless there are vast beds untouched, at lower levels, where the divers do not care to venture; and it is supposed that the outer face of the barrier-reef is probably one vast oyster-bed, but the bravest divers dare not venture to attempt work beneath the awful breakers.
Certain it is, that the colonies in the lagoons are annually replenished by myriads of infant pearl-oysters, which have been spawned in the deep sea, and which, in the months of December and March, may be seen floating in with the rising tide; tiny glittering shells, a quarter or a half inch in diameter, like fairy coins. Once in those calm waters, the young oysters apparently have no wish again to seek the stormy outer seas, for they are never seen floating out with the retiring tide. It takes seven years for an oyster to attain maturity, so only those which settle in deep water have a chance of reaching a ripe age.
Strange to say, these creatures, which appear to be so immovably attached to their coral-rock, are proved to be migratory. Not only do the closely packed young oysters detach their silken cables and move off in search of more roomy quarters, but even the heavy grown-up shells sometimes travel from one shelf in the coral to another, probably in search of better feeding-grounds. They are singularly capricious in the selection of their homes; in one lagoon they are abundant, and perhaps in the very next not an oyster is to be found: and no attempt to raise artificial beds, even by transporting masses of rock covered with young shells, has ever succeeded, although the surroundings are apparently identical in every respect. Of course they will not settle anywhere near sand, which, by any disturbing cause, might enter their shells, and cause them as much inconvenience as do the innumerable tiny red crabs,— uninvited guests, which take up their quarters in the oyster-shells, to the great aggravation of the helpless owners.
The lagoons in which these fisheries are carried on are' indescribably lovely: marine gardens, in which every detail of beauty is enhanced by being seen through the clearest crystal waters, which lend a glamour as of a magic glass to everything seen through them, whether sea-weed or shell, zoophyte or coral, gliding snake or rainbow-coloured fish Here and there are patches of pure white coral-sand, which serve to reveal the exquisite colour of the aqua-marine water; while the golden sea-weeds appear purple, and the corals seem to vary in hue, according to the depth at which they lie beneath the surface. It is all illusion, for the flowers of the sea are always disappointing when gathered. But there on the coral-ledges lie the great oysters and many other shells, including the huge clam, which is accounted excellent food. The pearl-oyster is only eaten in times of scarcity, as it is very coarse and unpalatable, though not unwholesome.
Diving for clams generally falls to the share of the women; and many a one has met her doom from getting nipped by the ponderous dentated shell, and so held prisoner in the depths, never to rise again. I heard several horrible stories on this subject in Fiji, and here new ones are added to the list. Quite recently a poor fellow fishing on one of the Paumotu atolls dived to the bottom of the lagoon, feeling for pearl-oysters, when he unluckily slipped the fingers of his left hand into a gaping clam-shell, which instantly closed and held him as if in a vice. The shell lay in a hole in the coral, so that it was impossible to reach the byssus by which it was moored in that safe harbour; the wretched man, in agony of mind and of body, severed his own fingers with his knife, and rose to the surface, having indeed escaped drowning, but being maimed for life. There have been other cases when a diver, thus imprisoned, has with greater deliberation contrived to insert his knife into the shell', and so force it open sufficiently to release his other hand.
In gathering clams, the aim of the diver is to stab the gaping mollusc with a sharp-pointed stake, and then with his knife cut the silky filaments by which it adheres to the rock, after which he slips both hands below the huge shell, and endeavours to raise it; DANGERS OF CLAM-FISHERS. 263
—no easy matter, considering what ponderous monsters many of the clams are—a single shell making an admirable bath for a child, pure as white marble, and highly polished by nature. In many Roman Catholic churches these large shells are used for holy water. The smaller clams, such as are generally used for food, are often picked up on the reef in basket-loads; and many a careless child has playfully thrust its little fingers into a gaping shell, an invasion promptly resented by the owner. Happily the scream of agony generally brings some friends to the rescue: and strong as is the armour of the poor besieged clam, it offers one weak point to the enemy—namely, the cavity through which the byssus passes; a skilful stab through this aperture causes the inmate to relax its hold, and so the child is released—but many a finger is lost in this manner. The multitude of these shell-fish annually consumed on all the isles is something incredible, and the supply is apparently inexhaustible. It is not generally known that these shells also occasionally yield very valuable and lustrous pearls of peculiar brilliancy.
But the treasury of the sea, which lies safe beyond the reach of covetous human beings, is that clean coral-sand which glimmers far below the coral-caves where the oysters congregate, and to which, for untold ages, have dropped the pearls which fell from the gaping shell, when the seven-year-old oyster, having lived his appointed time, melted away in his native brine, and let go the treasures he could no longer clasp. What a dream of delight, even in fancy, to gather up those
"Pale glistening pearls and rainbow-coloured shells,
I suppose the water-babies of these seas look upon pearls as we used to look on John o' Groats—probably with less reverence, as being so much more common; and perhaps they are right, for the one was only a disease, and the other a wondrously contrived little home.
One valuable creature which loves the white coral-sand as cordially as the pearl-oyster dreads it, is the black bSche-de-mer,1 a
1 llolothnroides. Chinese name, Tripang.