BOEA BORA. 161 



tide and direction of the wind. TLiere is a marked contrast in the character 

 of the barrier reefs of the Society Islands and those of the Fiji Islands. 

 While the barrier reefs have taken a great development off the larger islands 

 of Vanua Levu and Viti Levu, we do not find at the smaller volcanic islands 

 in Fiji such wide barrier reef flats upon the surface of which incessant move- 

 ment of material takes place as in the Society Islands. There are no islands 

 where the barrier reefs have taken such an extraordinary development as they 

 have in the Societv Islands. Along the northern extremity of Tahaa huge 

 flat pieces of reef rock or beach rock are found scattered on the barrier reef 

 flat. The material on this part of the reef platform apparently moves in 

 and out according to the supply on the flats, or according to the supply 

 driven out from the inner part of the lagoon. Some of the islets appear to 

 be wasting away, while others in close proximity are inci'easing in size. 



South of Iriru Pa.ss the east shore of Raiatea is flanked with 

 numerous volcanic islets. South of Faatemu Bay lies Haaio Island, 

 a volcanic islet of considerable size placed in the centre of the lagoon ; off 

 the west coast between Punaeroa Pass and Tiano Pass numerous volcanic 

 islets are enclosed within the shore fringing reef or rise from the deeper 

 parts of the lagoon. South of the Tiano Pass the lagoon of the western 

 coast is broken up into separate basins by the extension seaward of the 

 fringing reef and patches in lagoons towards the barrier reef flats. The 

 highest point of Piaiatea is about 3400 feet, while Tahaa is not more than 

 2000 feet high. 



Bora Bora. 



Plafes 96. fiff. 3; 07-103, 202; 210, fy. 3; 235. 



Tlie most striking of the Leeward Islands of the Society Islands is 

 undoubtedly Bora Bora. The wide barrier reef flat which surrounds 

 the central islands is edged with islands and islets. Many of them are 

 of considerable size. The reef flat is widest on the south and west 

 coasts, its greatest width is about one and a quarter miles (PI. 210, 

 fitf. .3) on the northwest flat. The low island of Teveiroa is covered with 

 a scanty vegetation, and extends across the whole width of the barrier 



