144 THE THEORY OF EVOLUTION 



animal life of spiders, flies, bugs, beetles, butterflies; 

 even lizards more than two feet long animated the 

 peaceful picture." In this instance, however, the 

 distance from land was not very great, or else the 

 restocking would have required a very much longer 

 time. 



The oceanic islands have no land mammals, except 

 bats, which like birds are often carried immense dis- 

 tances by strong gales. That this lack of mammals 

 is due to the impossibility of reaching the islands 

 and not to any unfitness to support the mammals is 

 made clear by the artificially introduced rabbits, 

 rats, mice, pigs, goats and cattle, which have, on 

 many such islands, thriven and multiplied exceed- 

 ingly. They also lack Amphibia, for frogs and 

 toads, newts and salamanders, their eggs and larvae, 

 cannot long endure immersion in sea- water; real 

 fresh-water fishes, crayfishes and shells, as distin- 

 guished from those which readily enter rivers from 

 the sea, are likewise wanting. Birds and insects 

 are brought by the winds, reptiles, especially lizards, 

 and snails are carried on driftwood, and it is only 

 such groups that occur in the oceanic islands. 



The observations which Darwin made in the 

 Galapagos, a volcanic group about 500 miles from 

 the coast of Ecuador, will serve as a type of what 

 may be learned from the life of oceanic islands. 

 Leaving out of account the sea-birds, which can 

 traverse the widest expanses of sea, the birds, rep- 

 tiles and plants of the Galapagos for the most part 



