The geographical distribution of animals, with a study of the relations ...

;52 DISTRIBUTION OF ANIMALS. [part i.genus ; and that belongs to an Order, " Insectivora," entirelyabsent from South America, and to a family, " Centetidae," allthe other species of which inhabit Madagascar only. And asif to add force to this singular correspondence we have oneMadagascar species of a beautiful day-flying Moth, Urania, allthe other species of which inhabit tropical America. Theseinsects are gorgeously arrayed in green and gold, and areunlike any other Lepidoptera upon the globe.The island of Ceylon generally agrees in itsquiteproductions withthe Southern part of India;yet it has several birds which areallied to Malayan and not to Indian groups, and a fineof the genus HcsHa, as well as severalare purely Malayan.butterflygenera of beetles, whichVarious important groups of animals are distributed in away not easy to explain. The anthropoid apes in West Africaand Borneo ; the tapirs in Malaya and South America ; thecamel tribe in the deserts of Asia and the Andes ; the trogonsin South America and Tropical Asia, with one species in Africa;the marsupials in Australia and America, are examples.The cases here adduced (and they might be greatly multiplied)are merely to show the kind of problems with which thenaturalist now has to deal ; and in order to do so he requiressome system of geographical arrangement, which shall servethe double purpose of affording a convenient subdivisionsubject, and at the same time of givingof hisexpression to the mainresults at which he has arrived. Hence the recent discussionson " Zoological Eegions," or, what are the most naturalprimary divisions of the earth as regards its forms of animallife.The divisions in use till quite recently were of two kindseither those ready made by geographers, more especially thequarters or continents of the globe ; or those determined byclimate and marked out by certain parallels of latitude or byisothermal lines. Either of these methods was better thannone at all; but from the various considerations explained inthe preceding chapters, it will be evident, that such divisionsmust have often been very unnatural, and have disguised many