io6 READINGS IX EVOLUTION, GENETICS, AND EUGENICS 



conditions of the South American coast; in fact, there is a considerable 

 dissimilarity in all these respects. On the other hand, there is a con- 

 siderable degree of resemblance in the volcanic nature of the soil, in the 

 climate, height, and size of the islands, between the Galapagos and Cape 

 de Verde Archipelagoes; but what an entire and absolute difference 

 in their inhabitants! The inhabitants of the Cape de Verde Islands 

 are related to those of Africa, like those of the Galapagos to America. 

 Facts such as these admit of no sort of explanation on the' ordi- 

 nary view of independent creation; whereas in the view here main- 

 tained it is obvious that the Galapagos Islands would be likely to 

 receive colonists from America, and the Cape de Verde Islands from 

 Africa; such colonists would be liable to modification — the principle of 

 inheritance still betraying their original birthplace. " 



The following is a synopsis of the fauna and flora of this archi- 

 pelago, so far as at present known. The only terrestrial vertebrates 

 are two peculiar species of land- tortoise, and one extinct species; five 

 species of lizards, all peculiar — two of them so much so as to constitute 

 a peculiar genus; — and two species of snakes, both closely allied to 

 South American forms. Of birds there are 57 species, of which no less 

 than 38 are peculiar; and all the non-peculiar species, except one, 

 belong to aquatic tribes. The true land-birds are represented by 31 

 species, of which all, except one, are peculiar; while more than half 

 of them go to constitute peculiar genera. Moreover, while they are 

 all unquestionably allied to South American forms, they present a 

 beautiful series of gradations, "from perfect identity with the conti- 

 nental species, to genera so distinct that it is difficult to determine with 

 what forms they are most nearly allied; and it is interesting to note 

 that this diversity bears a distinct relation to the probabilities of, 

 and facilities for, migration to the islands. The excessively abund- 

 ant rice-bird, which breeds in Canada, and swarms over the whole 

 United States, migrating to the West Indies and South America, 

 visiting the distant Bermudas almost every year, and extending its 

 range as far as Paraguay, is the only species of land-bird which remains 

 completely unchanged in the Galapagos; and we may therefore con- 

 clude that some stragglers of the migrating host reach the islands 

 sufficiently often to keep up the purity of the breed" [Wallace]. 

 Again, of the thirty peculiar land-birds, it is observable that the 

 more they dift'er from any other species or genera on the South 

 American continent, the more certainly are they found to have their 

 nearest relations among those South American forms which have the 



