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

chap, xin.] THE AUSTRALIAN REGION. 393varied forms of life in the Oriental region ;to which, possessinggreat powers of flight, some species must occasionally have emigrated.Its presence or absence serves therefore to define andlimit the Australian region with a precision hardly to beequalled in thebirds.case of any other region or any other family ofThe Trichoglossidse, as already intimated, are another of thesepeculiarly organized Australian families,— parrots with an extensilebrush-tipped tongue, adapted to extract the nectar andpollen from flowers. These are also rigidly confined to thisregion, but they do not range so completely over the whole of it,being absent from New Zealand (where however they are representedby a closely allied form Nestor),and from the SandwichIslands. The Paradiseidse (birds of paradise and allies) areanother remarkable family, confined to the Papuan group ofIslands, and the tropical parts of Australia. The Megapodiidse(or mound-builders) are another most remarkable and anomalousgroup of birds, no doubt specially adapted to Australian conditionsof existence. Their peculiarity consists in their layingenormous eggs (at considerable intervals of time) and buryingthem either in the loose hot sand of the beach above high-watermark, or in enormous mounds of leaves, sticks, earth, and refuseof all kinds, gathered together by the birds, whose feet andclaws are enlarged and strengthened for the work. The warmthof this slightly fermenting mass hatches the eggs ; when theyoung birds work their way out, and thenceforth take care ofthemselves, as they are able to run quickly, and even to fly shortdistances, as soon as they are hatched.This may perhaps be anadaptation to the peculiar condition of so large a portion ofAustralia, in respect to prolonged droughts and scanty watersupply,entailing a periodical scarcity of all kinds of food.In sucha country the confinement of the parents to one spot during thelong period of incubation would often lead to starvation, and theconsequent death of the offspring.But the same birds with freepower to roam about, might readily maintain themselves.Thispeculiar constitution and habit, which enabled the Megapodii tomaintain an existence under the unfavourable conditions of theirVol. I.—27