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Show 270 PHYSIOGNOMY OF PLANTS. this eastern peninsula are situated the cl;lains of Cochin China, Siam, and Malacca which are parallel with each other, as well as those of Ava and Arracan which all, after courses of unequal length, terminate in the Gulfs or Bays of Siam, Martaban, and Bengal. The Bay of Bengal appears like an arrested attempt of nature to form an inland sea. A deep invasion of the ocean, between the simple western system of the Ghauts, and the eastern very complex trans-Gangetic system of mountains, has swallowed up a large portion of the low lands on the eastern side, but met with an obstacle more difficult to overcome in the existence of the extensive high plateau of the Mysore. Such an invasion of the ocean has occasioned two almost pyra,. midal peninsulas of very different dimensions, and differently proportioned in breadth and length; and the continuations of two mountain systems (both running in the direction of the meridian, i. e. the mountain system of Malacca, on the east, and the Ghauts of Malabar on the west) show themselves in submarine chains of mountains or symmetrical series of islands, on the one side in the Andaman and Nicobar Islands which are very poor in corals, and on the other side in the three long-extended groups or series of Atolls of the Laccadives, Maldives, and the Chagos. The latter series, called by navigators the Chagos-bank, forms a lagoon encircled by a narrow and already much broken, and in great measure submerged, coral reef. The longer and shorter diameters of this lagoon, or its length and breadth, are respectively 90 and 70 geographical miles. Whilst the enclosed lagoon is only from seventeen to forty fathoms deep, the depth of water at a small distance from the outer margin of the coral (which appears to be gradually sinking) is such, that at half a mile no bottom was found in sounding with a line of 190 fathoms, and, at a somewhat greater distance, none with 210 fathoms. (Darwin, Structure of Coral Reefs, p. 39, 111, and 183.) At the coral lagoon called Keeling-Atoll, Captain Fitz-Roy, at a distance of only two thousand yards from the reef, found no soundings with 1200 fathoms. "The corals which, in the Red Sea, form thick wall-like masses, are species of Meandrina, Astrrea, Favia, Madrepora (Porites), Pocillopora (hemprichii), Millepora, and Heteropora. The latter are |