INHABITANTS OF OCEANIC ISLANDS. 387 



Zealand gigantic wingless birds, take, or recently took, the 

 place of mammals. Although New Zealand is here spoken 

 of as an oceanic island, it is in some degree doubtful 

 whether it should be so ranked ; it is of large size, and is 

 not separated from Australia by a profoundly deep sea ; from 

 its geological character and the direction of its mountain 

 ranges, the Rev. W. B. Clarke has lately maintained that this 

 island, as well as New Caledonia, should be considered as 

 appurtenances of Australia. Turning to plants, Dr. Hooker 

 has shown that in the Galapagos Islands the proportional 

 numbers of the different orders are very different from what 

 they are elsewhere. All such differences in number, and the 

 absence of certain whole groups of animals and plants, are 

 generally accounted for by supposed differences in the phj^si- 

 cal conditions of the islands ; but this explanation is not a 

 little doubtful. Facility of immigration seems to have been 

 fully as important as the nature of the conditions. 



Many remarkable little facts could be given with respect 

 to the inhabitants of oceanic islands. For instance, in 

 certain islands not tenanted by a single mammal, some of 

 the endemic plants have beautifully hooked seeds ; yet few 

 relations are more manifest than that hooks serve for the 

 transportal of seeds in the wool or fur of quadrupeds. But 

 a hooked seed might be carried to an island by other 

 means ; and the plant then becoming modified would form an 

 endemic species, still retaining its hooks, which would 

 form a useless appendage, like the shrivelled wings under 

 the soldered wing-covers of many insular beetles. Again, 

 islands often possess trees or bushes belonging to orders 

 which elsewhere include only herbaceous species ; now trees, 

 as Alph. de Candolle has shown, generally have, whatever the 

 cause may be, confined ranges. Hence trees would be little 

 likely to reach distant oceanic islands ; and an 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 

 over-topping 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. 



