STRUCTURH OF CORAL ISLANDS. 163 
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same extent.. Standing on the north shore of the Raraka la- 
goon and looking southwest, nothing is seen but blue waters. 
Far in the distance to the right, and also to the left, a few 
faint dots are observed; and as the eye sweeps around in 
either direction, these dots gradually enlarge and pass into lines 
of verdure, and finally, distinct groves near the observer. At 
Dean’s Island, another of the Paumotus, and at some of the 
Carolines, the resemblance to the ocean is still more striking. 
The lagoon is in fact but a fragment of the ocean cut off by 
more or less perfect walls of coral reef-rock; and the reef is 
here and there surmounted by verdure, forming a series of 
islets. 
In many of the smaller coral islands, the lagoon has lost 
its ocean character, and become a shallow lake, and the green 
islets of the margin have coalesced in some instances into a 
continuous line of foliage. Traces may perhaps be still de- 
tected of the passage, or passages, over which the sea once com- 
municated with the internal waters, though mostly concealed 
by the trees and shrubbery which have spread around and 
completed the belt of verdure. The coral island is now in its 
most finished state; the lake rests quietly within its circle of 
palms, hardly ruffled by the storms that madden the sur- __ 
rounding ocean. ibs 
From the islands with small lagoons, there is every variety 
in gradation down to those in which there is no trace of a la- 
goon. These simple banks of coral are the smallest of coral 
islands. In all the larger islands the windward side is the 
highest ; and sometimes it is wooded and habitable through- 
out when the leeward reef is bare. The entrances to the la- 
goons are accordingly on the leeward side. 
A single group of islands, the Gilbert or Kingsmill, af- 
fords good examples of the principal varieties. It is at once 
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