GEOGRAPHICAL DISTRIBUTION 191 



beetles. Again, islands often possess trees or bushes 

 belonging to orders which elsewhere include only her- 

 baceous species; now trees, as Alph. de CandoUe has 

 shown, generally have, whatever the cause may be, con- 

 fined ranges. Hence trees would be little likely to reach 

 distant oceanic islands; and a herbaceous plant, which 

 had no chance of successfully competing with the many 

 fully developed trees growing on a continent, might, 

 when established on an island, gain an advantage over 

 other herbaceous plants by growing taller and taller and 

 overtopping them. In this case, natural selection would 

 tend to add to the stature of the plant, to whatever 

 order it belonged, and thus first convert it into a bush 

 and then into a tree. 



Absence of Batrachians and Terrestrial Mammals on 



Oceanic Islands 



With respect to the absence of whole orders of 

 animals on oceanic islands, Bory St. Vincent long ago 

 remarked that Batrachians (frogs, toads, newts) are never 

 found on any of the many islands with which the great 

 oceans are studded. I have taken pains to verify this 

 assertion, and have found it true, with the exception of 

 New Zealand, New Caledonia, the Andaman Islands, and 

 perhaps the Salomon Islands and the Seychelles. But I 

 have already remarked that it is doubtful whether New 

 Zealand and New Caledonia ought to be classed as 

 oceanic islands; and this is still more doubtful with 

 respect to the Andaman and Salomon groups and the 

 Seychelles. This general absence of frogs, toads, and 

 newts on so many true oceanic islands cannot be ac- 

 counted for by their physical conditions: indeed it seems 



