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"These animals (he says) are of a great variety of shapes and sizes, and in such prodigious numbers, that in a short time the whole surface of the rock appears to be alive and in motion. The most common of the worms was in the form of a star, with arms from four to six inches long, which it moved about with a rapid motion in all directions, probably in search of food. Others were so sluggish, that they were often mistaken for pieces of the rock; these were generally of a dark color, and from four to five inches long, and two or three round.

"When the rock was broken from a spot near the level of high water, it was found to be a hard, solid stone; but if any part of it were detached at a level to which the tide reached every day, it was discovered to be full of worms, of all different lengths and colors: some being as fine as a thread, and several feet long, generally of a very bright yellow, and sometimes of a blue color; while others resembled snails; and some were not unlike lobsters and prawns in shape, but soft, and not above two inches long."

Probably it was with the minute description in mind of some closely observing navigator in Eastern seas, that the accomplished author of the finely conceived Poem called "The Pelican Island," adds this as a sequel to the coral-forming process which he has been most accurately describing:

A point at first
It peered above those waves; a point so small,
I just perceived it, fixed where all was floating;

MICROSCOPIC MOSS CORALS.

191

And when a bubble crossed it, the blue film , Expanded like a sky above the speck:

That speck became a hand-breadth; day and night

It spread, accumulated, and ere long

Presented to my view a dazzling plain,

White as the moon amid the sapphire sea;

Bare at low water, and as still as death,

But when the tide came guggling o'er the surface,

'Twas like a resurrection of the dead:

From graves innumerable, punctures fine

In the close coral, capillary swarms

Of reptiles, horrent as Medusa's snakes,

Covered the bald-pate reet Then all was life,

And indefatigable industry:

The artisans were twisting to and fro

In idle-seeming convolutions; yet

They never vanished with the ebbing surge,

Till pellicle on pellicle, and layer

On layer, was added to the growing mass.

Ere long the reef o'ertopped the spring-flood's height,

And mocked the billows when they leapt upon it,

Unable to maintain their slippery hold,

And falling down in foam-wreaths round its verge.

There is a variety of coral, of microscopic minuteness in its structure, of which the naturalists Ehrenberg and D'Orbigny have discovered hundreds of fossil species; and their minute shelly cases enter into the composition of chalk-beds, compact mountain limestone, the sea-sand of Europe, the Mauritius, the Sandwich Islands, and the sands of the Libyan desert, ev^n.

Some idea of the minuteness of these fossil moss corals may be formed from the fact, that in the finest levigated whiting multitudes are present, without having suffered change in the preparation of the chalk. Only let the microscope be employed, and a mosaicwork of moss-coral animalcules may be seen, of varied and beautiful forms, on the chalk-coating of the walls of a room.

The best way of observing them is to place a drop of water on a delicate film of mica, and to add to it as much fine chalk-powder as the top of a penknife will take up. Spread this out like a very thin layer, then drain off the water, and with it the floating particles; when the layer is quite dry, coat it over with pure Canada balsam, holding it, while this is being done, over a spirit-lamp. Then the powder, examined through a microscope, will be found chiefly composed of minute cells, the relics of moss corals.

Since the publication of the Annals of the U. S. Exploring Squadron, and especially the late volume of its Geology, by James D. Dana, Geologist of the Expedition, science has no lack of materials for describing and classifying the various species of coral zoophytes, their localities, modes, and probable times of growth. The facts furnished by this Expedition are almost innumerable; and in the superb quarto volume on Geology they are arranged in such a felicitous scientific order, (though, from the vast amount of original matter, necessarily diffuse,) as to afford the coral naturalist all the information he could desire.

The author's own deductions are clear and philosophical, and being derived from no partial knowledge of facts, they constitute a most valuable exhibiFEJEE ISLAND REEFS DESCRIBED.

193

tion of the conclusive and comprehensive logic of Modern Science. His view of the formation and growth both of reefs and corals agrees substantially with that presented above, and derived from our observations around the Island of Molokai.

His description of the inner reefs in the Fejees might answer almost equally well for this island. Examples are common there where, as in the account I have given of our ten miles sail upon the Molokai reef, a remote barrier incloses as pure a sea as the ocean beyond, and the greatest agitation is only such as the wind may excite on a narrow lake or channel. Over the surface there are many portions still under water at the lowest tides; and fine fishing sport is afforded on them to the natives, who wade out at the ebb-tide with spears, pronged sticks, and nets, to supply themselves with food

"The lover of the marvellous may find abundant gratification by joining in such a ramble. Among coral plants and flowers, with fishes of fantastic colors —star-fish, echini, and myriads of other beings, which science alone has named, fit inhabitants of a coral world—there is on every side occasion for surprise and admiration. Generally, the rock of these inner reefs is composed of coral, which stands as it grew, less fragmentary than the outer, but united by a solid cement. Upon its surface the limits of the constituent masses may be often distinctly traced. The corals grow underneath the surface in

solid hemispheres; but when the surface is reached the top dies, and enlargement only goes on at the sides.

"Some individual specimens of Porites, in the rock of the inner reef of Tongatabu, were twenty-five feet in diameter; and Astreas and Meandrinas, both there and in the Fejees, measured twelve to fifteen feet. The platform resembles a Cyclopean pavement, except that the cementing material between the huge masses is more solid than any work of art could be.

"Sometimes the barrier reef recedes from the shore, and forms wide channels or inland seas, where ships find ample roome and depth of water, exposed, however, to the danger of hidden reefs. The reef on the northeast coast of New Holland and New Caledonia extends four hundred miles, at a distance varying from thirty to sixty miles from shore, and having as many fathoms of depth in the channel. West of the large Fejee Islands the channel is in some parts twenty-five miles wide, and twelve to forty fathoms in depth. The sloop of war Peacock sailed along the west coast of both Viti Lebu and Vanua Lebu, within the inner reefs, a distance exceeding two hundred miles.

"A barrier reef, inclosing a lagoon, is the general formation of the coral islands, though there are some . of small size in which the lagoon is wanting. These are found in all stages of development: in some the reef is narrow and broken, forming a succession of narrow islets with openings into the lagoon; in others there only remains a depression of surface in the centre to indicate where the lagoon originally was. The

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