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sometimes through the whole circuit of an island; and not unfrequently ships may pass, as by an internal canal, from harbor to harbor around the island.

The reef is covered by the sea at high tide, yet the smoother waters indicate its extent and a line of breakers its outline. Occasionally a green islet rises from the reef, and in some instances a grove of palms stretches along the barrier for miles, where the action of the sea has raised the coral structure above the waves.

Coral islands resemble the reefs just described, except that a lake or lagoon is encircled instead of a mountainous island. A narrow rim of coral reef, generally but a few hundred yards wide, stretches around the inclosed waters. In some parts it is so low that the waves are still dashing over it into the lagoon, and in others it is verdant with the rich foliage of the tropics. The coral-made land when highest is seldom over eight or ten feet in height.

When first seen from the deck of a vessel, only a series of dark points are descried just above the horizon. Shortly after, the points enlarge into the plumed tops of the cocoanut trees, and a line of green, interrupted at intervals, is traced along the water's surface. Approaching still nearer, the lake and its belt of verdure are spread out before the eye, and a scene of more interest can scarcely be imagined. The surf beating loud and heavy along the margin of the reef, presents a strange contrast to the prospect beyond the white coral beach, the massy foliage of the grove, and the embosomed lake with its tiny islets. ***. Very erroneous ideas prevail respecting the appearance of a bed or area of growing corals. The submerged reef is often thought of as an extended

mass of coral, alive uniformly over its upper surface, and by this living growth gradually enlarging upward; and such preconceived views when ascertained to be erroneous by observation, have sometimes led to skepticism with regard to the zoophyte origin of the reef rock. Nothing is wider from the truth, and this must have been inferred from the description already given. Another glance at the coral plantation should be taken by the reader, before proceeding with the explanations which follow.

Coral plantation and coral field are more appropriate appellations than coral garden, and convey a juster impression of the surface of a growing reef. Like a spot of wild land, covered in some parts with varied shrubbery, in other parts bearing only occasional tufts of vegetation over barren plains of sand, here a clump of saplings, and there a carpet of variously colored flowers—such is the coral plantation.

Numerous kinds of zoophytes grow scattered over the surface, like the vegetation of the land. There are large areas that bear nothing, and others that are thickly overgrown. There is no green sward to the landscape, and here the comparison fails. Sand and fragments fill up the bare intervals between the flowering tufts, or where the zoophytes are crowded; there are deep holes among the stony stems and folia, that seem as if formed among the aggregated roots of the living corals.

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These fields of growing coral spread over submarine lands, such as the shores of islands and continents, where the depth is not greater than their habits require—just as vegetation extends itself through regions that are congenial. The germ or ovule, which, when first produced, swims free, finds afterwards a

point of rock or dead coral to plant itself upon, and thence springs the tree or some other form of coral growth.

ANALOGY TO VEGETATION.

The analogy to vegetation does not stop here. It is well known that the debris of the forest, decaying leaves and stems, and animal remains, add to the soil, and that accumulations of this kind are ceaselessly in progress; that by this means, in the luxuriant swamp, deep beds of peaty earth are formed. So it is in the coral mead. Accumulations of fragments and sand from the coral zoophytes, and of shells and other relics of organic life, are in constant progress, and thus a bed of coral debris is formed and compacted.

There is this difference-that a large part of the vegetable material consists of elements which escape as gases on decomposition; whereas, coral is itself an enduring rock material, undergoing no essential change except the mechanical one of comminution, the animal portion is but a mere fraction of the whole zoophyte.

In these few hints we have the whole theory of reef making; not a speculative opinion, but a legitimate deduction from a few simple facts, and bearing close analogy on land. The coral debris and shells fill up the intervals between the coral patches and the cavities among the living tufts, and in this manner produce the reef deposit, which is consolidated by the filtrating sea-water, having more or less lime in solution.

(Notes from U. S. Ex. Expedition in 1838, '39, '40, '41 and '42; James D. Dana, A. M., Geol. of Ex.)

AUSTRALIA.

The leviathan of the island groups of the world, Australia (literally South Asia), lies between latitude. 10 deg. 43 min. and 39 deg. 9 min. south, and longitude 113 deg. 15 min. and 153 deg. east, comprising within its vast limits three million square miles. It has a sea-coast of over eight thousand miles, along the line of which eighty-two small islands are located. Australia was discovered about 1606 by the Dutch, who were the first to locate it and chronicle its existence in modern times. It was first named by them New Holland, a name retained for many years.

From the sea this great island-continent presents an uninviting appearance, giving one the impression that the crags and mountains fringing the shores enclose a sterile waste within. Probably no country in the world has received more attention from men of science and explorers than Australia, and that, too, with less beneficial results, as the great mountain ranges and barren wastes of the interior are to-day as an unknown land.

One of the greatest detriments to its rapid progress in peopling and civilization, was its establishment as a penal colony by Great Britain. This, together with the low order of the native races, some two hundred thousand in number, who are little above the animal in the scale of humanity, proved for many years a great barrier to the peopling of the island with the better classes. Until 1851 the progress of Australia was under a ban; when Mr. Hargreaves, returning from the gold fields of California, discovered the precious metal on the island. From this time may be dated the advancement of that country. The gold

fever drew people from all parts of the world to settle on her shores. Cities and. towns rapidly sprang into existence, while the consequent development of great agricultural resources, fed with the thousand millions in gold taken from her mines, placed her at once among the great countries of the world. With the single exception of California, nothing like Australia's progress has occurred in ancient or modern times. The discovery of many valuable mines of copper, coal, tin, lead and silver followed that of gold, and being found in large and paying quantities, add largely to the income of the inhabitants.

PHYSICAL FEATURES.

The mountain ranges on the island are but few in number. The greatest altitude of those already discovered does not exceed seven thousand feet.

There are many ponds and swamps in the interior, with few navigable streams-only in the rainy season. Even then navigation is very uncertain, as the waters of most of the rivers frequently disappear -lost in the sands of the surrounding wastes.

The flora of the island is not varied or extensive, but two species forming the principal forest growththe eucalyptii and acacia—although more than one hundred varieties of each of these interesting species are found, and in great abundance.

GEOLOGICAL AND GEOGRAPHICAL.

The geological formation is quite an interesting study, partaking of the eruptic, metamorphic, trappean, with the sedimentary sandstones of the tertiary period.

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