If we exclude New Caledonia (⅞.v.), which is of older formation than the rest, all the islands of Polynesia are either of volcanic or of coral formation. Some are purely coral, either in the shape of low atolls or of elevated plateaus. In a few atolls there are remnants of earlier volcanic rocks; and most of the volcanic islands are more or less fringed with coral reefs. But, notwithstanding this mixture, the islands must be divided broadly into those which are volcanic and those which are of coral formation. The coral islands must again be subdivided into (1) atolls, or low islands which usually have a lagoon within them, and (2) elevated table-lands.

The volcanic islands, with the exception of the Hawaiian archipelago, are all south of the equator. In Plate III. the great volcanic ridge is indicated by two lines which, commencing in 150° E., run in a south-easterly direction to about 140° W. long. With the exception of two curves, one in the lower line south of the New Hebrides, and one in the upper line at its eastern extremity, these are parallel, and are 10° apart. Within these two lines lie all the volcanic islands of Polynesia, except two isolated groups, viz., the Marquesas and Hawaiian Islands. On this ridge there are no atolls. The upper boundary line sharply divides the volcanic ridge from the atoll valley. This valley is indicated by a third line running for more than 50° of longitude parallel with the other two, at 20° distance from that bounding the northern extremity of the volcanic ridge. Eastward of 155° W. long, this line bends towards the south to exclude the isolated volcanic centre of the Marquesas Islands; then, curving around the Tuamotu archipelago, it joins the central line. Within the area thus enclosed lie all the atolls or low coral lagoon islands of Polynesia, and there are no volcanic islands within this region except in three or four instances, where are found the remnants of former islands which have sunk, but have not been quite submerged. This is the region of subsidence —stretching across fully 100° of longitude, and covering generally about 20° of latitude.

Within the volcanic region there are a few coral islands, but these are all more or less elevated. Since their formation they have participated in the upward movement of the ridge on which they are situated. They are indicated on the map by dotted lines. Two of the groups are within the lines marking the volcanic ridge; and one, the Loyalty group, lies close to the lower line.

The Volcanic Islands. — Most of the volcanic islands of Polynesia are high in proportion to their size. The tapering peaks, or truncated cones, which form their backbone present a picturesque appearance to the voyager as he approaches them. In some there are precipitous spurs jutting into the sea, while in others the land slopes gently from the central peak to the shore. Where there are these gentle slopes, and wherever there is any low land near the shore, there also will be found a coral reef fringing the coast at a smaller or greater distance, according to the steepness of the land under the water. Where the trend downwards is very gradual, the edge of the reef will sometimes be one, two, or even three miles to seaward. It has been thought that the absence of extensive reefs in some islands of the New Hebrides is due to “subterranean heat.” But the steepness of the slope of the islands under water is doubtless the reason why the reefs are small. As the reef-building coral polypes do not live and work below a certain depth—about 20 fathoms, or 120 feet—we easily see that the distance of the outer edge of the reef must be according to the slope of the island beneath the water. Opposite to the larger valleys, where there is a stream flowing out to sea, there is usually found a break in the reef. This is doubtless caused either by the fresh water, or by the sediment which it contains, injuring the coral polypes and preventing them from effectively carrying on their work in these spots. The conviction of the present writer is that it is the sediment contained in the water—especially during heavy rains and consequent freshets—which prevents the growth of the coral, rather than the mere action of fresh water upon the polypes. Where there are streams of considerable βize, and especially where they are subject to floods, there are generally wide openings into the reef, and stretches of deep water forming natural harbours sufficient for the accommodation of even large vessels. There are a few land-locked harbours, but most are thus formed by breaks in the reef.

In a few spots active volcanoes are still found. These are in the neighbourhood of New Britain and New Ireland, in the Solomon, New Hebrides, and Tonga archipelagoes. In most of the islands there have been no recent eruptions; but now and again the inhabitants of islands where volcanic action has apparently long ceased have been startled by a new outbreak. Over the whole region earthquakes are of frequent occurrence. Most of the craters in the islands of Samoa have immense trees growing in them, and there is only one crater in the entire group which shows signs of even a comparatively recent eruption, or concerning which there is a tradition among the people of one. Yet in 1867, after an almost continuous succession of earthquakes during a whole night, there was a submarine eruption between two of the islands. This lasted only a few days. A few months afterwards the writer was on board H.M.S. “Falcon” when soundings were taken on the spot. A cone was found the summit of which was 90 fathoms deep, while all around the sea was 120 fathoms deep. Thus the outpourings of this submarine volcano during only a few days raised a mound in the bed of the ocean 180 feet in height.

The soil in the volcanic islands is generally very fertile. The climate is hot and moist in most of them; consequently the vegetation is wonderfully rich. The islands are densely clothed with the most luxuriant verdure from the sea-beach to the summits of the mountains. While in a few islands, especially the comparatively barren ones (barren is only a comparative term as applied to any of the volcanic islands), there is sometimes grand and bold scenery, in most of them the jagged and precipitous rocks are so covered up and rounded off with the rich vegetation that they lose much of their grandeur. The atmosphere is so laden with moisture that ferns, club-mosses, and even small shrubs grow upon the faces of the steepest rocks. Mainly on this account the scenery can rarely be said to be grand; but nearly all these islands are truly beautiful. There is a freshness about the vegetation all the year round which is rarely seen in other portions of the world. The cocoa-nut palm groves, which are usually abundant on the low lands near the sea, always give a charm to the islands as they are approached. In addition to several species of palms, beautiful ferns, dracaenas, crotons, and other elegant foliage plants abound. Pines are found on some of the western islands. For flowers none of them will compare with the hedgerows and meadows of England. There are, it is true, many most beautiful and sweet-scented flowers, but they are not usually found in great profusion.

Fruits are abundant. Some of the indigenous kinds are good, and many of the best productions of other tropical countries have been introduced and flourish. Oranges are very plentiful in many islands; also pine-apples, guavas, custard apples, and bananas. The mango has been introduced into some islands, and flourishes well. Most of these fruits have been introduced by missionaries. One of the fruits most abundantly used, both in a ripe state and cooked when unripe as a vegetable, is the Chinese banana, Musa Cavendishii. The first plant of this carried to the islands was in a case of plants given by the duke of Devonshire to the missionary John Williams when he returned from England to the Pacific shortly before he was killed on Erromanga. During the long voyage all the plants in the case died except this banana.

When it reached Samoa it was carefully cultivated by one of the missionaries and a stock of it was propagated. From the single plant all the Chinese bananas in Polynesia have sprung, and, that particular kind being greatly prized both by natives and foreign settlers, it is now grown largely wherever missionaries or traders have gone, and must produce annually hundreds of tons of nutritious food.

The natives live chiefly upon vegetable food. In most of the volcanic islands the taro (Colocasia esculenta) is the most important food-producer. Next to this comes the yam (Dioscorea sativa). Probably next in importance to this are the plantains and bananas, then the bread-fruit (Artocarpus incisa) and arrowroot (Tacca pinnatijida). The bread-fruit is more or less plentiful in most of the volcanic islands, and during one season of the year the natives very largely subsist upon it. It is not, however, by any means so nutritious as the taro or the yam. This vegetable is often spoken of in Britain as if it were a rich fruit, but one would as soon eat a raw potato as a raw bread-fruit. It has been over-estimated by many writers who have visited the Pacific. The present writer has noticed that the Samoans suffered in condition, that sickness among children was very common and the rate of mortality high during the bread-fruit season. Although the raw cocoa-nut is not eaten to any considerable extent by the natives of volcanic islands, this must not be omitted in an enumeration of the principal articles of their food supply, for it enters into the composition of most of their made dishes in the form of expressed juice or oil; the soft half-grown kernel is used as a kind of dessert, and the liquid from it, when the kernel is only half developed, is one of their principal beverages. The Ava, or Kava, a narcotic drink largely used, is made from the root of a pepper (Piper methysticum).

In some islands the cocoa-nut is t'he chief article of commerce. The fully-grown kernel is cut into slices, dried in the sun, and sold as “cobra,” from which much of the palm oil of commerce is expressed. On many islands cotton is largely grown, and on a few, especially in the Hawaiian archipelago, sugar cultivation has made considerable progress. Many other vegetable products might be utilized if there were a demand for them. The candle-nut (Aleurites triloba) is abundant everywhere near the coast. Coffee has not been grown to any considerable extent. Wild ginger and wild nutmegs are abundant on some of the islands. In some places indigo has been introduced, and has spread so much as to become a nuisance. All the islands have numerous valuable fibre-producing plants belonging to the Urticeae and Malvaceae. But the probability is that, on these hot, moist, and fertile islands, cocoa-nuts, cotton, or sugar will always be the most profitable crops to cultivate for exportation.

The indigenous fauna of Polynesia is poor in mammals but rich in birds. Mammals are represented by rats and bats, the latter including the flying foxes (Pteropus). Some say pigs are indigenous, but they were doubtless introduced by early navigators. Horses and cattle have been introduced. They degenerate very rapidly, unless they are continually improved by newly-imported stock. Sheep and goats are introduced into some islands, but sheep do not usually thrive. Dogs are plentiful, being kept by most of the natives, who are naturally fond of domestic animals; but they degenerate greatly. Pigeons and doves, especially the fruit-eating pigeons {Carpophaga) and doves of the genus Ptilonopus, are abundant. The Carpophaga furnish a very important article of food in some of the islands. Some of the species of Ptilonopus are exceedingly beautiful. Megapodes are found in a few of the western islands; the kagu (Rhinochetus jubatus) has its home on New Caledonia; and in Samoa the Didunculus strigirostris has its habitat. This bird is remarkable as being the nearest relative of the extinct dodo. Some time ago it was rarely found, and was becoming extinct. It fed and nested on the ground, and was destroyed by cats and rats after they were introduced. Of late it has changed its habits: it now feeds, nests, and roosts upon trees, and is, in consequence, increasing in numbers. Certain non-venomous snakes are found in many of the islands. Insect life is abundant, and some of the butterflies are very beautiful.

The lagoons formed by the coral reefs around the islands invariably abound in fish, many of them most gorgeous in their colouring,—vying in this respect with the parrots of Australia. Fish form a very important part of the food supply.

One of the most wonderful creatures in the marine fauna of Polynesia is the palolo (Palola viridis), an annelid which appears upon the surface of the ocean, near the edge of the coral reef, at certain seasons of the year. The palolo are from 9 to 18 inches long, and about ⅛th of an inch thick. They are eaten by the natives, and are esteemed a great delicacy. They live in the interstices of the coral reef, and are confined to a few localities. About 3 o’clock on the morning following the third quartering of the October moon they invariably appear upon the surface of the water; generally they are in such quantities that they may be taken up by the handful. Soon after the sun rises they begin to break, and by 9 o’clock a. Μ. they have broken to pieces and disappeared. The morning following the third quarter of the November moon they again appear in the same manner, but usually in smaller quantities. After that they are not again seen until October of the next year. They appear thus to deposit their ova, which is done by the breaking to pieces of the female worms; the males also break in the same manner, the ova being fertilized while floating in the water. Thus the parents are destroyed in propagating their species. The eggs gradually sink down to the reef where they are hatched. The young papolo then live about the reef until the next year, when they repeat the process. Year by year these creatures appear according to lunar time. Yet, in the long run, they keep solar time. This they do by keeping two cycles, one of three years and one of twenty-nine years. In the short cycle there are two intervals of twelve lunations each, and one of thirteen lunations. These thirty-seven lunations bring lunar time somewhat near to solar time. But in the course of twenty-nine years there will be sufficient difference to require the addition of another lunation; the twenty-ninth year is therefore one of thirteen instead of twelve lunations. In this way they do not change their season during an entire century. So certain has been their appearance that in Samoa they have given their name to the spring season, which is vae-p ιlolo, or the time of palolo. The Atolls.— The atolls differ in almost every respect from the islands of volcanic origin. Little that is said of one class would be true of the other. These coral islands are all low, generally not more than 10 or 12 feet above high-water mark. They are simply sandbanks formed by the accumulation of debris washed on to the reefs during strong winds. Hence they are usually in the shape of a narrow band, varying from a few yards to one-third of a mile across, near the outer edge of the reef, with a lagoon in the centre. In some of the smaller atolls the circle of land is almost or entirely complete, but in most of those of larger dimensions there are breaks to leeward, and the sea washes freely over the reef into the lagoon. Where the circle of land is complete the sea-water gains access to the central lagoon through the reef underneath the islands. In some it bubbles up at the rise of the tide in the midst of the lagoons, forming immense natural fountains. This has been observed producing a specially fine effect at Nui in the Ellice group. Some of these atolls are not more than 3 or 4 miles in their greatest length. Others are many miles long. They are not all circular, but are of all conceivable shapes.

Two of the atolls known to the present writer are remarkable. The lagoons in them are of fresh water. One of these is Lakena in the Ellice group, the other Olosenga, or Quiros Island, in ll 0 2' S. lat. and 17Γ W. long. Both are small circular islands, and in both the lagoon is shut off from the sea. Olosenga is less than 4 miles in diameter, the lagoon occupying over 3 miles, leaving a ring of land around it less than half a mile across. In some places the lagoon is at least 6 fathoms deep. This bulk of fresh water cannot, therefore, be the result of drainage. There is much to favour the opinion that both this island and Lakena are situated over the craters of former volcanoes, and that there is submarine connexion between them and some of the larger islands situated on the volcanic ridge from which the body of fresh water must come. Olosenga is about 200 miles distant from Samoa. In that group mountain streams sometimes fall into chasms and totally disappear underground. In this way subterranean lakes may be formed in some of the cavities which we may suppose volcanic eruptions to leave. It is not difficult to suppose that there would be subterranean connexion between these lakes and an isolated crater 200 miles distant. If so, as the crater participated in the subsidence of the region on the edge of which it is situated, the water would rise in it until, if the supply were sufficient, it there found an outlet. This appears to be what occurs at Olosenga. The lake has never been properly examined and sounded. It is, however,- of considerable depth in the centre, where the water is said sometimes to bubble up as if from a great spring, and at low tide it is seen to percolate through the sand on the outer or sea side of the land.

The vegetation of the atolls is extremely poor, not more than about fifty species of plants being found in the Tokelau, Ellice, and Gilbert groups, in all of which groups collections have been made. All the species consist of littoral plants found in the volcanic islands. Most of them have their seeds enveloped in thick husks, which specially fit them for being carried by currents. Doubtless it is in this way that the atolls have received their flora. The cocoa-nut is abundant on most of these islands. This most useful palm will grow on any sandbank in the tropics, and it is benefited by having its roots in soil saturated with sea water. Unlike the natives of volcanic islands, those dwelling on the atolls eat the raw kernel...