Chap. XIT. OCEANIC ISLANDS. 391 



marine birds could arrive at these islands more easily than 

 land-birds. Bermuda, on the other hand, which lies at 

 about the same distance from North America as the 

 Galapagos Islands do from South America, and which 

 has a very peculiar soil, does not possess one endemic 

 land bird; and we know from Mr. J. M. Jones's ad- 

 mirable account of Bermuda, that very many North 

 American birds, during their great annual migrations, 

 visit either periodically or occasionally this island. 

 Madeira does not possess one peculiar bird, and many 

 European and African birds are almost every year blown 

 there, as I am informed by Mr. E. V. Harcourt. So that 

 these two islands of Bermuda and Madeira have been 

 stocked by birds, which for long ages have struggled 

 together in their former homes, and have become mutu- 

 ally adapted to each other ; and when settled in their 

 new homes, each kind will have been kept by the others 

 to their proper places and habits, and will consequently 

 have been little Liable to modification. Madeira, again, 

 is inhabited by a wonderful number of peculiar land- 

 shells, whereas not one species of sea-shell is confined 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 far more 

 easily than land-shells, across three or four hundred 

 miles of open sea. The different orders of insects in 

 Madeira apparently present analogous facts. 



Oceanic islands are sometimes deficient in certain 

 classes, and their places are apparently occupied by 

 the other inhabitants ; in the Galapagos Islands reptiles, 

 and in New Zealand gigantic wingless birds, take the 

 place of mammals. In the plants of the Galapagos 

 Islands, Dr. Hooker has shown that the proportional 

 numbers of the different orders are very different from 



