AUSTRALIAN BARRIER-REEF.—The limits of this great reef, which has already been described, have been coloured from the charts of Flinders and King. In the northern parts, an atoll-formed reef, lying outside the barrier, has been described by Bligh, and is coloured dark blue. In the space between Australia and New Caledonia, called by Flinders the Corallian Sea, there are numerous reefs. Of these, some are represented in Krusenstern’s “Atlas” as having an atoll-like structure; namely, _Bampton_ shoal, _Frederic_, _Vine_ or Horse-shoe, and _Alert_ reefs; these have been coloured dark blue. LOUISIADE: the dangerous reefs which front and surround the western, southern, and northern coasts of this so-called peninsula and archipelago, seem evidently to belong to the barrier class. The land is lofty, with a low fringe on the coast; the reefs are distant, and the sea outside them profoundly deep. Nearly all that is known of this group is derived from the labours of D’Entrecasteaux and Bougainville: the latter has represented one continuous reef ninety miles long, parallel to the shore, and in places as much as ten miles from it; coloured pale blue. A little distance northward we have the _Laughlan_ Islands, the reefs round which are engraved in the “Atlas of the Voyage of the ‘Astrolabe’,” in the same manner as in the encircled islands of the Caroline Archipelago, the reef is, in parts, a mile and a half from the shore, to which it does not appear to be attached; coloured blue. At some little distance from the extremity of the Louisiade lies the _Wells_ reef, described in G. Hamilton’s “Voyage in H.M.S. ‘Pandora’” (page 100): it is said, “We found we had got embayed in a double reef, which will soon be an island.” As this statement is only intelligible on the supposition of the reef being crescent or horse-shoe formed, like so many other submerged annular reefs, I have ventured to colour it blue.