€hap. XIII.] ON OCEANIC ISLANDS. 351 



Islands, which are inhabited by a wolf-like fox, come nearest to an 

 exception ; but this group cannot be considered as oceanic, as it 

 lies on a bank in connection with the mainland at the distance of 

 about 280 miles ; moreover, icebergs formerly brought boulders to 

 its western shores, and they may have formerly transported foxes, 

 as now frequently happens in the arctic regions. Yet it cannot be 

 said that small islands will not support at least small mammals, 

 for they occur in many parts of the world on very small islands, 

 when lying close to a continent; and hardly an island can be 

 named on which our smaller quadrupeds have not become natu- 

 ralised and greatly multiplied. It cannot be said, on the ordinary 

 view of creation, that there has not been time for the creation of 

 mammals ; many volcanic islands are sufficiently ancient, as shown 

 by the stupendous degradation which they have suffered, and by 

 their tertiary strata : there has also been time for the production 

 of endemic species belonging to other classes ; and on continents 

 it is known that new species of mammals appear and disappear at 

 a quicker rate than other and lower animals. Although terrestrial 

 mammals do not occur on oceanic islands, aerial mammals do occur 

 on almost every island. New Zealand possesses two bats found 

 nowhere else in the world : Norfolk Island, the Viti Archipelago, 

 the Bonin Islands, the Caroline and Marianne Archipelagoes, and 

 Mauritius, all possess their peculiar bats. Why, it may be asked, 

 has the supposed creative force produced bats and no other mam- 

 mals on remote islands ? On my view this question can easily be 

 answered ; for no terrestrial mammal can be transported across a 

 wide space of sea, but bats can fly across. Bats have been seen 

 wandering by day far over the Atlantic Ocean ; and two North 

 American species either regularly or occasionally visit Bermuda, at 

 the distance of 600 miles from the mainland. I hear from Mr. 

 Tomes, who has specially studied this family, that many species 

 have enormous ranges, and are found on continents and on far 

 distant islands. Hence we have only to suppose that such wan- 

 dering species have been modified in their new homes in relation 

 to their new position, and we can understand the presence of 

 endemic bats on oceanic islands, with the absence of all other 

 terrestrial mammals. 



Another interesting relation exists, namely between the depth 

 of the sea separating islands from each other or from the nearest 

 continent, and the degree of affinity of their mammalian inha- 

 bitants. Mr. Windsor Earl has made some striking observations 

 on this head, since greatly extended by Mr. Wallace's admirable 

 researches, in regard to the great Malay Archipelago, which is 



