180 INHABITANTS OF OCEANIC ISLANDS. [Chap. Xlll 



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 ISTorth American 

 birds occasionally or even frequently visit this island. 

 Almost every year, as I am informed by Mr. E. V. 

 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 to- 

 gether, 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 

 modification. Any tendency to modification will also 

 have been checked by intercrossing with the un- 

 modified immigrants, often arriving from the mother- 

 country. Madeira again is inhabited by a wonder- 

 ful 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 transported across three or four hun- 

 dred miles of open sea far more easily than land-shells. 

 The different orders of insects inhabiting Madeira pre- 

 sent nearly parallel cases. 



Oceanic islands are sometimes deficient in animals of 

 certain whole classes, and their places are occupied by 

 other classes; thus in the Galapagos Islands reptiles. 



