XV111 DESCRIPTION OF PLATES. 



the Voyage of the Chev. Dillon ; the other soundings are laid down 

 from the survey by D'Urville ; height of the summit of the is- 

 land is 3,032 feet. The principal small detached reefs within 

 the lagoon-channel have in this instance been represented. The 

 southern shore of the island is narrowly fringed by a reef ; if the 

 engraver had carried this reef entirely round both islands, this 

 figure would have served (by leaving out in imagination the bar- 

 rier-reef) as a good specimen of an abruptly-sided island, sur- 

 rounded by a reef of the fringiDg class. 



.Fig. 2. — Hogoleu, or Boug, in the Caroline Archipelago ; taken from 

 the atlas of the Voyage of the Astrolabe, compiled from the surveys 

 of Captains Duperrey and D'Urville ; scale ^ of an inch to a mile ; 

 the depth of the immense lagoon-like space within the reef is not 

 known. 



Fig. 3. — Kaiatea, in the Society Archipelago ; from the map given in 

 the quarto edition of Cook's First Voyage ; it is probably not accurate ; 

 scale ^ of an inch to a mile. 



Fig. 4. — Bow, or Heyctj atoix (or lagoon-island), in the Low Archi- 

 pelago ; from the survey by Capt. Beechey, B.N. ; scale ^ of an inch 

 to a mile ; the lagoon is choked up with reefs, but the average 

 greatest depth of about 20 fathoms, is given from the published 

 account of the voyage. 



Fig. 5. — Bolabola, in the Society Archipelago ; from the survey of 

 Capt. Duperrey, in the Coquille ; scale \ of an inch to a mile ; the 

 soundings in this and the following figure have been altered from 

 French feet to English fathoms ; height of highest point of the 

 island 4,026 feet. 



Fig. 6. — Matjrua, in the Society Archipelago ; from the survey by 

 Capt. Duperrey in the Coquille ; scale \ of an inch to a mile ; height 

 of land about 800 feet. 



Fig. 7. — Pouynipete, or Seniavine, in the Caroline Archipelago ; from 

 the survey by Admiral Lutke ; scale \ of an inch to a mile. 



Fig. 8. — GtAMBier Islands, in the southern part of the Low Archi- 

 pelago ; from the survey by Capt. Beechey ; scale \ of an inch to a 

 mile; height of highest island, 1,246 feet ; the islands are surrounded 

 by extensive and irregular reefs ; the reef on the southern side is 

 submerged. 



Fig. 9. — Peros Banhos atoll (or lagoon-island), in the Chagos group 

 in the Indian Ocean ; from the survey by Capt. Moresby and Lieut. 



