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Show 408 JSLAND LIFE. (PART II. reached the group by means of intervening islauds afterwards submerged, and to have thenceforth remained to increase and multiply unchecked by the attacks of an_y mor~ powerful animals we can well understand that the wmgs, bemg useless, would in time become almost aborted.1 It is also n?t improbable that this process would be aided by nat~ra~ ~election, because the use of wings might be absolutely preJudwml to the birds in their new home. Those that flew up into trees to roost, or tried to cross over the mouths of rivers, might be blown out to sea and destroyed, especially during the hurricanes which have probably always more or less devastated t_he isl~nd~;. while on the other hand the more bulky and short-wmged mdtvtduals, who took to sleeping on the ground in the forest, would be preserved from such dangers, and perhaps also from the attacks of birds of prey which may always have visited the islands. But whether or no this wns the mode by which these singular birds acquired their actual form and structure, it is perfectly certain that their existence and development depended on complete isolation and on freedom from the attacks of enemies. We have no single examp~e of such defenceless birds having ever exis~ed on a continent at any geological period, whereas analogous 1 That the dodo is really an abortion from a more perfect type, and not a direct development from some lower form of wingless bird, is shown by its possessing a keeled sternum, though the keel is exceedingly reduced, being only three-quarters of an inch deep in a length of seven inches. The most terrestrial pigeon-the Didunculns of the Samoan islands, bas a far deeper and better developed keel, showing that in the case of the dodo the degradation has been extreme. vVe have also analogous examples in other extinct birds of the same group of islands, such as the flightless RailsAphanapteryx of Mauritius and Erythromachus of Rodriguez, as well as the large parrot-Lopbopsittacus of Mauritius, and the Night Heron, Nycticorax rnegacephala of Rodriguez, the last two birds probably having been able to fly a little. The commencement of the sawe process is to be seen in the peculiar dove of the Seychelles, TU?·tur t·ost?·atus, which, as Mr. Edward Newton bas shown, has much shorter wings than its close ally, 1'. picturatus, of Madagascar. For a full and interesting account of these and other recently extinct birds see Professor Newton's article on "] ossil Birds" in the Encyclopmdia B1·itannica, ninth edition, vol. iii., p. 732; and that on "The Extinct Birds of Rodriguez," by Dr. A. Giintlter and Mr. E. Newton, in the Hoyal Society'~::~ volume on t]Je Transit of Venus Expedition. CHAP. XIX.l 'l'HE MADAGASCAR GROUP. 409 though totally distinct forms do exist in New Zealand, \Vhere enemies are equally wanting. On the other hand, every continent has always produced abundance of carnivora adapted to prey upon the herbivorous animals inhabiting it at the same period; and we may therefore be sure that these islands have never formed part of a continent during any portion of the time when the dodos inhabited them. It is a remarkable thing that an ornithologist of Dr. Hartlaub's reputation, looking at the subject from a purely ornithological point of view, should yet entirely ignore the evidence of these wonderful and unique birds against his own theory, when he so confidently characterises Lemuria as "that sunken land which, containing parts of Africa, must have extended far eastward over Southern India and Ceylon, and the highest points of which we recognise in the volcanic peaks of Bourbon and Mauritius, and in the central range of Madagascar itself-the last resorts of the mostly extinct Lemurine race which formerly peopled it." 1 It is here implied that lemurs formerly inhabited Bourbon and Mauritius, but of this there is not a particle of evidence, and we feel pretty sure that had they done so the dodos would never have been developed there. In Madagascar there are no traces of dodos, while there are remains of extinct gigantic struthious birds of the genus JEpyornis, which were no doubt as well able to protect themselves against tbe smaller carnivora as are the ostriches, emus, and cassowaries in their respective countries at the present day. The whole of the evidence at our command, therefore, tends to establish in a very complete manner the "oceanic" character of the three islands-Mauritius, Bourbon, and Rodriguez, and that they have never formed part of" Lemuria," or of any continent. Reptiles.-Mauritius, like Bourbon, has lizards, some of which are peculiar species; but no snakes, and no frogs or toads but such as have been introduced.2 Strange to say, however, a small islet called Round Island, only about a mile across, and 1 See lbis, 1877, p. 334. 2 A common Indian and Malayan toad (Bufo melanostictus) bas been introduced into Mauritius and also some European toads, as l am informed uy Dr. Giiutller. |
