10. Dyke, porphyritic granite, composed of white quartz, white feldspar, and bronze-coloured mica. This dyke cuts across the schistus last mentioned, in a direction north-east and south-west. It is nearly vertical, and varies in breadth from nine to forty feet, with numerous ramifications. 11. Dyke of compact whin stone. This dyke is composed of five layers of prisms, whose length is at right angles to the walls of the dyke. It is nearly vertical. Its direction north and south, and is about five feet thick. MAIN LAND OF COREA. 12. Lead-coloured, fine-grained, micaceous schistus. From the main land of Corea, latitude 36º 10' north, longitude 126º 48' east. The strata lie north-west and south-east, and are nearly vertical; the natives objected to our examining the cliffs, though distant less than a quarter of a mile from the beach. ANOTHER ISLAND OFF THE COAST OF COREA. Latitude 34º 23' north, longitude 126º east. 13. Decomposing fine-grained rock; composed of flesh-coloured feldspar, white quartz, and porcelain clay. ANOTHER ISLAND NEAR THE ABOVE. 14. Rock composed of white feldspar and quartz. The strata of this rock were very much contorted. This rock is the most general of any in this range of islands, at least as far as we had opportunities of examining them. The islands on this coast are very numerous; they lie in great clusters along a line of three degrees and a half of latitude. The islands vary in length from five or six miles to as many yards, and are of all forms. We saw none that were remarkably high, and none which seemed volcanic. As our stay on the coast was only nine days, and as the ships were almost always under weigh except at night, it was quite impossible to make any careful or valuable geological observations. It offers a splendid field to future voyagers. GREAT LOO-CHOO ISLAND. 1. Grey stratified lime-stone without shells. This specimen was taken from the north end of the island, where the ranges of hills were mostly composed of it: the strata being highly inclined. The hills rise to the height of four or five hundred feet, and present nothing interesting. 2. Fawn-coloured, cellular, granular lime-stone. The cliffs at Napakiang are composed of this rock; it also appears to stretch along the whole of the south-west and south parts of the coast. In the narrative, this rock has been erroneously called coral. These cliffs are curiously hollowed out into horizontal caves, which have all the appearance of having been worn by the dashing of the waves; but as it is obvious, that in their present situation the sea can never have reached the face of the cliffs, it seems probable that the whole coast may have been raised up, by a gentle movement, without dislocating the strata, or disturbing the horizontal position, in which it seems probable that these caves were formed.