280 ISLAND LIFE 



since they are found in a considerable number of islands 

 which possess no mammals nor any other land reptiles ; 

 but what those means are has not yet been positively 

 ascertained. (See Darwinism, 3rd ed. p. 374.) 



It is unusual for oceanic islands to possess snakes, and it is 

 therefore somewhat of an anomaly that two species are 

 found in the Galapagos. Both are closely allied to South 

 American forms, and one is hardly different from a Chilian 

 snake, so that they indicate a more recent origin than in 

 the case of the lizards. Snakes it is known can survive a 

 long time at sea, since a living boa-constrictor once 

 reached the island of St. Vincent from the Coast of South 

 America, a distance of two hundred miles by the shortest 

 route. Snakes often frequent trees, and might thus be 

 conveyed long distances if carried out to sea on a tree 

 uprooted by a flood such as often occurs in tropical climates 

 and especially during earthquakes. To some such accident 

 we may perhaps attribute the presence of these creatures 

 in the Galapagos, and that it is a very rare one is indicated 

 by the fact that only two species have as yet succeeded in 

 obtaining a footing there. 



Birds, — We now come to the birds, whose presence here 

 may not seem so remarkable, but which yet present 

 features of interest not exceeded by any other group. 

 Over a hundred species of birds have now been obtained on 

 these islands, and of these seventy-two are peculiar to them. 

 But all the species found elsewhere, except three, belong to 

 the aquatic tribes or the waders which are pre-eminently 

 wanderers, yet even of these nine are peculiar. The true 

 land-birds are sixty-six in number, and all but three are 

 entirely confined to the Galapagos ; while nearly five-sixths 

 of them present such peculiarities that they are classed in 

 distinct genera though all are allied to birds inhabiting 

 tropical America. Even the small number of the land- 

 birds which inhabit the American continent should be 

 reduced from three to two, since the rice-bird (Dolichonyx 

 oryzivorus) was an accidental straggler which has never 

 been found since Darwin obtained it on James Island. 



The following list of the land-birds, together with their 

 distribution in the several i^lands^ is extracted from Mr. 



