286 ISLAND LIFE part ii 



Darwin, and tlieir natural history carefully examined. 

 The, only mammals are rats, brought by a wrecked vessel 

 and said by Mr. Waterhouse to be common English rats, 

 '•' but smaller and more brightly coloured ; " so that we 

 have here an illustration of how soon a difference of race 

 is established under a constant and uniform difference of 

 conditions. There are no true land-birds, but there are 

 snipes and rails, both apparently common Malayan 

 species. Reptiles are represented by one small lizard, 

 but no account of this is given .in the Zoology of the 

 Voyage of the Beagle, and we may therefore conclude 

 that it was an introduced species. Of insects, careful 

 collecting only produced thirteen species belonging to 

 eight distinct orders. The only beetle was a small Elater, 

 the Orthoptera were a Gryllus and a Blatta; and there 

 were two flies, two ants, and two small moths, one a 

 Diopsea which swarms everywhere in the eastern tropics 

 in grassy places. All these insects were no doubt brought 

 either by winds, by floating timber (which reaches the 

 islands abundantly), or by clinging to the feathers of 

 aquatic or wading birds ; and we only require more time 

 to introduce a greater variety of species, and a better soil 

 and more varied vegetation, to enable them to live and 

 multiply, in order to give these islands a fauna and flora 

 equal to that of the Bermudas. Of wild plants there 

 were only twenty species, belonging to nineteen genera and 

 to no less than sixteen natural lamilies, wliile all were 

 common tropical shore plants.^ These islands are thus 

 evidently stocked by waifs and strays brought by the 

 winds and waves ; but their scanty vegetation is mainly 

 due to unfavourable conditions — the barren coral rock and 

 sand, of which they are wholly composed, together with 

 exj^osure to sea-air, being suitable to a very limited 

 number of species which soon monopolise the surface. 

 With more variety of soil and aspect a greater variety of 

 plants would establish themselves, and these would favour 

 the preservation and increase of more insects, birds, and 



1 ]\Ir. H. O, Forbes, who visited these islands in 1878, increased the 

 number of wikl plants to thirty-six, and these lielonged to twenty-six 

 natural orders. 



