72 CORAL FORMATIONS. 
Sydney Island.—Lat. 4° 20’ 8. Long. 171° 15’ W. Trending 
northeast and southwest. Well wooded nearly all round; but on 
leeward side the forest in patches, with breaks of bare coral. La- 
goon 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 consisted of coral frag- 
ments 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. 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 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' 8., 172° 27' W. Form irregularly oblong, 
trending northwest. Length 3% miles; breadth 2 miles. Circuit 9 
miles, and about one-half wooded in patches. Southwest reef mostly 
bare. A lagoon, but without entrance except for canoes at high tide, 
on leeward side. Island ten feet high. Shore platform narrow, and 
intersected by channels. Shores lined by reef-rock, two to three feet 
out of water, indicating an elevation of the island. This reef-rock 
consists of various corals firmly cemented. Within the lagoon, knolls 
of coral, but none near the shore on the leeward side. 
Fakaafo, or Bonditch’s.—9° 20' S., 171° 5’ W. 6% miles by 4. 
Shape nearly triangular. Circuit seventeen miles, about six of which 
are wooded in several patches, separated by long intervals. A large 
lagoon, but no ship entrance. Height of island, fifteen feet. Width to 
the lagoon, one hundred to two hundred yards. Soil of the island coral 
sand, speckled black with results of vegetable decomposition. Shore 
platform narrow. At outer edge a depth of three fathoms, and from 
thence gradually deepens, and abounds in fine corals for fifty yards, 
when it deepens abraptly. Coral reef-rock elevated three or four feet, 
indicating an elevation of the island. Lagoon shallow, with some 
growing coral, but none near the shore. Some corals growing on the 
platform, near its margin, mostly small Madrepores, Astreas, Nulli- 
pores. Fragments of pumice were found among the natives, which 
had been floated to the island.—See figure 5, page 53. 
Ahu, or Peacock’s Island, Paumotu Archipelago.—14° 30’ S., 146° 
20' W. 13 miles by 6, trending N.E. by E. Shape irregularly 
oblong. A large lagoon, having an entrance for small vessels, on the 
west. The reef wooded throughout nearly its whole circuit. Lagoon 
