The SOCIETY Archipelago is separated by a narrow space from the Low Archipelago; and in their parallel direction they manifest some relation to each other. I have already described the general character of the reefs of these fine encircled islands. In the "Atlas of the 'Coquille's' Voyage" there is a good general chart of the group, and separate plans of some of the islands. TAHITI, the largest island in the group, is almost surrounded, as seen in Cook's chart, by a reef from half a mile to a mile and a half from the shore, with from ten to thirty fathoms within it. Some considerable submerged reefs lying parallel to the shore, with a broad and deep space within, have lately been discovered ("Naut. Mag." 1836, page 264) on the N.E. coast of the island, where none are laid down by Cook. At EIMEO the reef "which like a ring surrounds it, is in some places one or two miles distant from the shore, in others united to the beach" (Ellis, "Polynesian Researches," volume i., page 18, 12mo edition). Cook found deep water (twenty fathoms) in some of the harbours within the reef. Mr. Couthouy, however, states ("Remarks," page 45) that both at Tahiti and Eimeo, the space between the barrier-reef and the shore, has been almost filled up,--"a nearly continuous fringing-reef surrounding the island, and varying from a few yards to rather more than a mile in width, the lagoons merely forming canals between this and the sea-reef," that is the barrier-reef. TAPAMANOA is surrounded by a reef at a considerable distance from the shore; from the island being small it is breached, as I am informed by the Rev. W. Ellis, only by a narrow and crooked boat channel. This is the lowest island in the group, its height probably not exceeding 500 feet. A little way north of Tahiti, the low coral-islets of TETUROA are situated; from the description of them given me by the Rev. J. Williams (the author of the "Narrative of Missionary Enterprise"), I should have thought they had formed a small atoll, and likewise from the description given by the Rev. D. Tyerman and G. Bennett ("Journal of Voyage and Travels," volume i., page 183), who say that ten low coral-islets "are comprehended within one general reef, and separated from each other by interjacent lagoons;" but as Mr. Stutchbury ("West of England Journal," volume i., page 54) describes it as consisting of a mere narrow ridge, I have left it uncoloured. MAITEA, eastward of the group, is classed by Forster as a high encircled island; but from the account given by the Rev. D. Tyerman and G. Bennett (volume i., page 57) it appears to be an exceedingly abrupt cone, rising from the sea without any reef; I have left it uncoloured. It would be superfluous to describe the northern islands in this group, as they may be well seen in the chart accompanying the 4to edition of Cook's "Voyages," and in the "Atlas of the 'Coquille's' Voyage." MAURUA is the only one of the northern islands, in which the water within the reef is not deep, being only four and a half fathoms; but the great width of the reef, stretching three miles and a half southward of the land (which is represented in the drawing in the "Atlas of the 'Coquille's' Voyage" as descending abruptly to the water) shows, on the principle explained in the beginning of the last chapter, that it belongs to the barrier class. I may here mention, from information communicated to me by the Rev. W. Ellis, that on the N.E. side of HUAHEINE there is a bank of sand, about a quarter of a mile wide, extending parallel to the shore, and separated from it by an extensive and deep lagoon; this bank of sand rests on coral-rock, and undoubtedly was originally a living reef. North of Bolabola lies the atoll of TOUBAI (Motou-iti of the "'Coquille's' Atlas") which is coloured dark blue; the other islands, surrounded by barrier-reefs, are pale blue; three of them are represented in Figures 3, 4, and 5, in Plate I. There are three low coral-groups lying a little E. of the Society Archipelago, and almost forming part of it, namely BELLINGHAUSEN, which is said by Kotzebue ("Second Voyage," volume ii., page 255), to be a lagoon-island; MOPEHA, which, from Cook's description ("Second Voyage," book iii., chapter i.), no doubt is an atoll; and the SCILLY Islands, which are said by Wallis ("Voyage," chapter ix.) to form a GROUP of LOW islets and shoals, and, therefore, probably, they compose an atoll: the two former have been coloured blue, but not the latter.
MENDANA OR MARQUESAS GROUP.
These islands are entirely without reefs, as may be seen in Krusenstern's Atlas, making a remarkable contrast with the adjacent group of the Society Islands. Mr. F.D. Bennett has given some account of this group, in the seventh volume of the "Geographical Journal". He informs me that all the islands have the same general character, and that the water is very deep close to their shores. He visited three of them, namely, DOMINICANA, CHRISTIANA, and ROAPOA; their beaches are strewed with rounded masses of coral, and although no regular reefs exist, yet the shore is in many places lined by coral-rock, so that a boat grounds on this formation. Hence these islands ought probably to come within the class of fringed islands and be coloured red; but as I am determined to err on the cautious side, I have left them uncoloured.
COOK OR HARVEY AND AUSTRAL ISLAND.
