326 ZOOLOGY OF
butterflies that the Amazonian forests are unrivalled, whether we consider the endless variety of the species, their large size, or their gorgeous colours. South America is the richest part of the world in this group of insects, and the Amazon seems the richest part of South America. This continent is distin- guished from every other by having a most extensive and peculiar family, the Jfelkoniidce, of which not a single species is found in either Europe, Asia, Africa, or even North America (excepting Mexico). Another family, still more extensive, of exquisitely beautiful small butterflies, the Erychiidce, is also almost peculiar to it, a few species only being found in tropical Asia and Africa. In both these peculiar families the Amazon is particularly rich, so that we may consider it as the head- quarters of South America Lepidoptera.
Para itself, for variety of species, is perhaps the best locality for diurnal Lepidoptera; six hundred distinct kinds may be obtained within a day's walk of the city. At Santarem I had increased my collection to seven hundred species, at Barra to eight hundred, and I should have brought home with me nine hundred species had my collections arrived in safety. Mr. Bates, who has paid more exclusive attention to insects, states that he has now obtained twelve hundred species, — a wonderful collection to be made by one person, in a country without any variation of climate or of physical features, and no part of it elevated five hundred feet above the level of the sea.
E. Geographical Distribution of Animals.
There is no part of natural history more interesting or instructive than the study of the geographical distribution of animals.
It is well known that countries possessing a climate and soil very similar, may differ almost entirely in their productions. Thus Europe and North America have scarcely an animal in common in the temperate zone ; and South America contrasts equally with the opposite coast of Africa ; while Australia differs almost entirely in its productions from districts under the same parallel of latitude in South Africa and South America. In all these cases there is a wide extent of sea separating the countries, which few animals can pass over; so
