254 



TOILERS IN THE SEA. 



no trace of it can be seen at the surface. It might 

 be supposed that when these atolls are called " coral 

 islands " they are really extensive surfaces of habit- 

 able land, but such is not the case, for the small 

 amount of habitable land they present is one of 







FIG. 53. CORAL LAGOON. 



their most peculiar features. Dana has shown that 

 in the Kingsmill group of ten islands, which have an 

 aggregate area of eighteen hundred and fifty square 

 miles, the actual amount of dry and habitable land 

 is only seventy-six miles, or less than one twenty- 

 fourth. In the Caroline Archipelago the proportion 



