CORAL ATOLLS 89 



sounds, which has been aptly styled the Italian of the 

 Pacific. In some cases, particularly when the natives 

 were not red men but black, they showed less favour to 

 strangers, and the islands sometimes became the theatre 

 of bloody strife. 



Besides man, whose presence is an additional problem 

 of the islands, no other mammals are indigenous, their 

 place being taken by various land crabs and spiders of 

 many kinds. 



An examination of the rocks of a low island reveals 

 another singular feature : save for a few fragments of 

 pumice, brought from distant volcanos by sea-currents 

 and cast by the waves upon the strand, they present us 

 with but one kind of material, carbonate of lime, which 

 has been extracted from solution in the sea, and built up 

 into a diversity of solid forms by the agency of organisms, 

 plants and animals, of which the most conspicuous are 

 corals. Thus but one kind of rock enters into the con- 

 stitution of the island, and this is limestone : of granite, 

 slate, sandstone, clay, such as we are familiar with at 

 home, there is none : all is limestone, whatever you 

 see ! 



The interest of this fact is enhanced by another. 

 Kepeated investigation has proved that the island is 

 not merely a residuum, a mortuary of calcareous 

 organisms, but that it is still alive and in active 

 growth. A profusion of gaily-tinted corals forms reefs 

 within the lagoon, and the whole of the shelving plat- 

 form, which descends from the surf to a distance of 20 

 or 30 fathoms below the sea, is alive with them : this 

 platform is indeed the true growing surface of the 

 island. 



Corals, by reason of their considerable size and brilliant 

 colours, first attract the attention of the observer, and 

 hence, although numerous other kinds of creatures col- 



