xvm 
DESCRIPTION OF PLATES. 
are given from the Voyage of the Chev. Dillon ; the other sound- 
ings are laid down from the survey by D’Urville ; height of the 
summit of the island is 3,032 feet. The principal small detached 
reefs within the lagoon-channel have in this instance been repre- 
sented. 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 imagina- 
tion the barrier-reef) as a good specimen of an abruptly-sided 
island, surrounded by a reef of the fringing class. 
Fig. 2. — Hogoleu, or Roug, 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 i of an inch 
to a mile ; the depth of the immense lagoon-like space within the 
reef is not known. 
Fig. 3. — Raiatea, in the Society Archipelago ; from the map given in 
the quarto edition of Cook’s First Voyage; it is probably not 
accurate ; scale i of an inch to a mile. 
Fig. 4. — Bow, or He von atoll (or lagoon-island), in the Low Arch 
pelago ; from the survey by Capt. Beechey, R.N. ; scale i 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 Goquille ; 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. — Maukua, in the Society Archipelago ; from the survey by 
Capt. Duperrey in the Goquille ; scale j of an inch to a mile ; 
height of land about 800 feet. 
Fig. 7. — Pouynipete, or Senlavine, in the Caroline Archipelago ; 
from the survey by Admiral Lutke ; scale of an inch to a mile. 
Fig. 8. — Gambler Islands, in the southern part of the Low Archi- 
pelago ; from the survey by Capt. Beechey ; scale J of an inch to 
a mile; height of highest island, 1,246 feet; the islands are sur- 
rounded 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 
