180 INHABITANTS OF OCEANIC ISLANDS. [Chap. XIII. 



South America, and which ha3 a very peculiar soil, 

 does not possess a single endemic land-bird; and we 

 know from Mr. J. M. Jones's admirable account of 

 Bermuda, that very many Xorth American birds occa- 

 sionally or even frequently visit this island. Almost 

 every year, as I am informed by Mr. E. Y. Harcourt, 

 many European and African birds are blown to 

 Madeira ; this island is inhabited by 99 kinds, of which 

 one alone is peculiar, though very closely related to a 

 European form ; and three or four other species are 

 confined to this island and to the Canaries. So that 

 the Islands of Bermuda and Madeira have been stocked 

 from the neighbouring continents with birds, which for 

 long ages have there struggled together, and have 

 become mutually co-adapted. Hence when settled in 

 their new homes, each kind will have been kept by 

 the others to its proper place and habits, and will 

 consequently have been but little liable to modifi- 

 cation. Any tendency to modification will also have 

 been checked by intercrossing with the unmodified 

 inmigrants, often arriving from the mother-country. 

 Madeira again is inhabited by a wonderful number of 

 peculiar land-shells, whereas not one species of sea- 

 shell is peculiar to its shores : now, though we do not 

 know how sea-shells are dispersed, yet we can see that 

 their eggs or larvae, perhaps attached to seaweed or 

 floating timber, or to the feet of wading-birds, might be 

 trans] orted across three or four hundred miles of open 

 sea far more easily than land-shells. The different 

 orders of insects inhabiting Madeira present nearly 

 parallel cas 5. 



Oceanic islands are sometimes deficient in animals of 

 certain whole classes, and their places are occupied by 



