CORAL REEFS, AND ISLANDS. 257 



still uncovered, many of the larger blocks of 

 coral, with their usual rough angular features and 

 blackened surface. There is but little depth of 

 coral soil, although the land may appear buried 

 in the richest foliage. In fact the soil is scarcely 

 anything but coral sand. It is seldom discoloured 

 beyond four or five inches, and but little of it to 

 this extent ; there is no proper vegetable mould, 

 but only a mixture of darker particles with the 

 white grains of coral sand. It is often rather a coral 

 gravel, and below a foot or two it is usually cemented 

 together into a more or less compact corals and rock." 1 

 The animals and plants found on these lagoon 

 islands consist of but few species, and these have 

 been enumerated by Darwin in his "Journal," 

 especially those found upon Keeling Island. " In 

 such a loose, dry, stony soil," he says, " the climate 

 of the intertropical regions alone could produce a 

 vigorous vegetation." " The cocoa-nut palm, at the 

 first glance, seems to compose the whole wood ; 

 there are, however, five or six other trees. Besides 

 the trees, the number of plants is exceedingly 

 limited, and consists of insignificant weeds. In 

 my collection, which includes, I believe, nearly the 

 perfect Flora, there are twenty species, without 

 reckoning a moss, lichen, and fungus. To this 



1 Dana, p. 143. 

 S 



