GENERAL FEATURES OF CORAL ISLANDS. 



2S 



3. 



4. 



swain's island. 





JARVIS ISLAND. 



Swain' ] s and Jarvis Islands, (figs. 

 3 and 4,) are of still smaller size, 

 and have no lagoon. The former 

 is densely covered with foliage, 

 while the surface of the latter is 

 sandy. S wain's Island is a little depressed about the centre, a 

 fact indicating that there was formerly a lagoon. 



Fakaafo, or Bowditch, (fig. 5. 



5,) 200 miles north of Samoa, is 

 the type of a large part of coral 

 islands. The bank of reef has 

 only here and there emerged 

 from the waves and become ver- 

 dant ; in other portions the reef 

 is of the usual height, — that is, 

 near low tide level, — excepting 

 a few spots elevated a little by 

 the accumulation of sand. 



The Panmotu Archipelago, the 

 crowded cluster of coral islands 

 just northeast of Tahiti, is a 

 most instructive study for the 

 reader ; and a map of these 

 islands by the Expedition^ in- 

 serted in the Narrative of the 

 Expedition, and also in the Hy- 

 drographical Atlas, will well re- 

 pay close examination. Sailing 

 among these islands — over eighty in number, only four of which 

 are over twelve feet high exclusive of the vegetation, — two or 

 three are almost constantly in sight from the mast-head. 



The small amount of habitable land on these reef-islands is 

 one of their most peculiar features. Nearly the whole surface is 

 water; and the land around the lagoon is but a narrow rim, the 

 greater part of which is usually under water at high tide. This 

 fact will be rendered more apparent from the following table, con- 

 taining a statement of the sizes and areas of several islands, with 

 the amount of habitable land. The measures are given in geo- 

 graphical miles. 



FAKAAFO. 





Length. 



Greatest breadth. 



Area in square 

 miles. 



Habitable parts in 

 square miles. 



Carlshoff, Paumotus, 



27 



13 



200 



10 



Wolchonsky, " 



15 



3 



40 



3 



Raraka, " 



15 



10 



90 



8 



Manhii, " 



14 



H 



50 



9 



Nairsa or Deans, " 



50 



19 



1000 



16 



Fakaafo, Union Group, 



n 



H 



20 



2i 



Clarence, " 



H 



H 



27 



2 



Taputeouea, Kingsmills, 



33 



6 



60 



6 



Tarawa, " 



20 



10 



130 



8 



Namouti, " 



22 



9 



125 



7 



Tari-tari, " 



18 



11 



110 



4 



