STRUCTURE OF CORAL ISLANDS. 199 



rock was bare, and contained numerous shells of TridacnaB. A 

 few small Madrepores still growing in the lagoon. Beach on 

 the sea-shore side eight feet high. In lower part of beach, sev- 

 eral layers of white limestone (the beach sand-rock), formed of 

 coral fragments or sand, shells, etc., much of which was very 

 compact. The layers inclined toward the sea at an angle of 

 about six degrees. Shore platform as elsewhere in this archi- 

 pelago. 



The facts above stated are evidence of a slight elevation, 

 probably not exceeding three feet. 



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

 144° 46' W. 2f miles by If, trending northwest, Has a 

 small lagoon with no entrance. Reef almost continuously 

 wooded around, somewhat broken into patches. 



Sydney Island.— 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 isl- 

 and from sea to lagoon, one hundred to four hundred yards : 

 width greatest at south end. Beach ten feet high. The soil of 

 the island consisted of coral fragments and sand. Shore plat- 

 form fifty to eighty feet wide ; five or six feet of water over it at 

 high tide. Cut up very irregularly by channels three to eight 

 or ten feet wide. Observed small corals growing on the bottom 

 outside of the platform. Shores of lagoon shallow for fifty 

 yards, and consisting of coral sand. Beyond this a slope cov- 

 ered 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 irregu- 

 larly oblong, trending northwest. Length 3f miles ; breadth 

 2 miles. Circuit 9^ miles, and about one^half wooded in 



