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ftvi ilfili are also 



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 ,. -'c. rarelj 



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rhap ,, 



■ Ch. XLIX.] 



DEPTH AT WHICH COEALS GROW. 



585 



There is every variety of form in coral reefs, but tlie most 

 remarkable and numerous in the Pacific consist of circular 



or 



oval strips of dry land, enclosing a shallow lake or 



la<^'Oon of still water, in which zoophytes and moUusca abound. 

 The annular reefs just raise themselves above the level of the 

 sea, and are surrounded by a deep and often unfathomable 

 ocean. 



In the annexed cut (fig. 152), one of these circular islands 



Fig. 152. 



View of Whitsunday Island. (Capt. Beechcy.)* 



is represented, just rising above the waves, covered with the 

 cocoa-nut and other trees^ and enclosing within a lagoon of 

 tranquil water. 



The accompanying section will enable the reader to com- 

 prehend the usual form of such islands. (Fig. 153.) 



Fig. 153. 



Section of a Coral Island. 



«, a. Habitable part of the island, consisting of a strip of coral, enclosing the lagoon. 

 &, 6. The lagoon. 



The subjoined cut (fig. 154) exhibits a small part of the 

 section of a coral island on a larger scale. 



Of thirty-two of these coral islands visited by Beechey in 

 his voyage to the Pacific, twenty-nine had lagoons in their 



* Voyage to the Pacific, &c. in 1825-28. 



I 



