STRUCTURE OF CORAL ISLANDS. 39 



surface in many parts very rough. It seemed surprising at all 

 these islands to find so luxuriant a growth of trees and shrubbery 

 over so rocky a surface. Shores of the lagoon nearly flat. On 

 one side there was a large area of extremely fine coral sand and 

 mud, which extended a long distance into the lagoon. Elsewhere- 

 about the centre of the island, the reef-rock was bare, and con- 

 tained numerous shells of Tridacnas. A few small Madrepores 

 still growing in the lagoon. Beach on the sea-shore side eight 

 feet high. In lower part of beach, several layers of white lime- 

 stone, (the beach sandrock,) formed of coral fragments or sand r 

 shells, &c, much of which was very compact. The layers 

 inclined towards the sea at an angle of about five degrees. 

 Shore platform as elsewhere in this archipelago. 



The facts above stated are evidence of a slight elevation, not 

 exceeding two or three feet. 



Taiara, or King's, Paumotu Archipelago. — 15° 42' S. ; 144° 

 46' W. 2§ miles by If, trending northwest. A small lagoon with, 

 no entrance. Reef almost continuously wooded around, some- 

 what broken into patches. 



Maraki, Tarawan or Kingsmills Group. — 5 miles by 2, and 

 having a lagoon. Trending north. Shape oblong triangular. 

 Belt of forest complete. Appearance of a former entrance to 

 the lagoon on the east side. 



W/iytuhu, one of the two Disappointment Islands, Paumotu 

 Archipelago. — 14° 10' S., 141° 24' W. 5 J by 2 miles, trending 

 northwest. The reef fronting northeast almost continuously 

 wooded. On the opposite side, three islets, one of rather largo 

 size. Lagoon with no entrance. 



Sydney Islcmd.—Lat 4° 20' S. Long. 171° 15' W. Trends 

 northeast and southwest. Well wooded nearly all round; but 

 on leeward side the forest in patches, with breaks of bare coral. 

 Lagoon narrow, without entrance. Width of island from sea 

 to lagoon, one hundred to four hundred yards: width greatest 

 at south end. Beach ten feet high. The soil of the island con- 

 sisted of coral fragments and sand. Shore platform fifty to eighty 

 feet wide ; five or six feet water over it at high tide. Cut up 

 very irregularly by channels three to eight or ten feet wide. Ob- 

 served small corals growing on the bottom outside of the plat- 

 form. Shores of lagoon shallow for fifty yards, and consisting 

 of coral sand. Beyond this a slope covered with growing corals. 

 The corals rather tender species of Madrepores. In the interior 

 of the lagoon many knolls and large patches of coral. 



Duke~of York's.— 8° 38' S., 172° 27' W. Form irregularly 

 oblong, trending northwest. Length 3| miles ; breadth 2 miles. 

 Circuit 9J miles, and aboui one half wooded in patches. South- 

 west reef mostly bare. A lagoon, but without entrance except 

 for canoes at high tide, on leeward side. Island ten feet high. 



