chap, i.] INTRODUCTORY. 



Having thus defined our subject, let us glance at the opinions 

 that have generally prevailed as to the nature and causes of 

 the phenomena presented by the geographical distribution of 

 animals. 



It was long thought, and is still a popular notion, that the 

 manner in which the various kinds of animals are dispersed 

 over the globe is almost wholly due to diversities of climate and 

 of vegetation. There is indeed much to favour this belief. The 

 arctic regions are strongly characterised by their white bears 

 and foxes, their reindeer, ermine, and walruses, their white 

 ptarmigan, owls, and falcons ; the temperate zone has its foxes 

 and wolves, its rabbits, sheep, beavers, and marmots, its sparrows 

 and its song birds ; while tropical regions alone produce apes and 

 elephants, parrots and peacocks, and a thousand strange quadru- 

 peds and brilliant birds which are found nowhere in the cooler 

 regions. So the camel, the gazelle and the ostrich live in the 

 desert ; the bison on the prairie ; the tapir, the deer, and the 

 jaguar in forests. Mountains and marshes, plains and rocky 

 precipices, have each their animal inhabitants ;• and it might well 

 be thought, in the absence of accurate inquiry, that these and 

 other differences would sufficiently explain why most of the 

 regions and countries into which the earth is popularly divided 

 should have certain animals peculiar to them and should want 

 others which are elsewhere abundant. 



A more detailed and accurate knowledge of the productions of 

 different portions of the earth soon showed that this explanation 

 was quite insufficient ; for it was found that countries exceed- 

 ingly similar in climate and all physical features may yet have 

 very distinct animal populations. The equatorial parts of Africa 

 and South America, for example, are very similar in climate 

 and are both covered with luxuriant forests, yet their animal life 

 is widely different; elephants, apes, leopards, guinea-fowls 

 and touracos in the one, are replaced by tapirs, prehensile- 

 tailed monkeys, jaguars, curassows and toucans in the other. 

 Again, parts of South Africa and Australia are wonderfully 

 similar in their soil and climate ; yet one has lions, antelopes, 

 zebras and giraffes ; the other only kangaroos, wombats, phalan- 



