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Show 406 IS LAND LIFE. [rART II. s::ttellites, that it is absolutely necessary to associate the~ toget~er if we wish to comprehend and explain their many mterestmg features. Mauritius and Bourbon are lofty volcanic islands, evidently of great antiquity. They are about 100 miles apart, ~nd the sea between them is less than 1,000 fathoms deep, whtle on each side it sinks rapidly to depths of 2,400 and 2,600 fathoms. We have therefore no reason to believe that they have ever been connected with Madagascar, and this view is strongly supported by the character of their indigenous fauna. Of this, however, we have not a very complete or accurate knowledge, for though both islands have long been occupied by Europeans, the study of their natural products was for a long time greatly neglected, and owing to the rapid spread of sugar cultivation, the virgin forests, and with them no doubt many native animals, have been almost wholly destroyed. There is, however, no good evidence of there ever having been any indigenous mammals or amphibia, though both are now found and are often recorded among the native aniruals.1 1 In Maillard's Notes sttr l'.fsle de Reu.nion, a considerable number of mammalia are given as "wild," such as Lernur mongoz and Centetes setosus, both Madagascar species, with such undoubtedly introduced animals as 11. wild cat, a bare, and several rats and mice. He also gives two species of frogs, seven lizards, and two snakes. The latter are both Indian species and certainly imported, as are most probably the frogs. Legouat, who resided some years in the island nearly two centuries ago, and who was a close observer of nature, mentions numerous birds, large bats, landtortoises, and lizards, but no other reptiles or venomous animals except scorpions. We mny be pretty sure, therefore, that the land-mammalia, snakes, and frogs, now found wild, have all been introduced. Of lizardB, on the other hand, there are several species, some peculiar to the island, others common to Africa and the other Mascarene Islands. The following list by Prof. Dumeril is given in Maillard's work:- Platydactylus cPpedianus. , ocellatus. Hemidactylus peronii. , rnutilatus. Hemidacty lus frenatus. Gongylus bojerii. A blepharus per01~ii. Four species of chameleon are now recorded from Bourbon and one from Mauritius (J. Reay Greene, M.D., in Pop. Science Rev. April, 1880), but as they are not mentioned by the old writers, it is pretty certain th at theso creatures are recent introductions, and this is the more probable as they are favourite domestic pets. CUAr. XIX.] TilE MADAGASCAR GHOUP. 407 The smaller and more remote Rodriguez is also volcanic; but it has, besides, a good deal of coralline rock, an indication of partial submergence and helping to account for the poverty of its faunas and flora. It stands on a 100-fathom bank of considerable extent, but beyond this the sea rapidly deepens to more than 2,000 fathoms, RO that it is truly oceanic like its larger sister isles. Bi1·ds.-The living birds of these islands are few in number and consist mainly of peculiar species of Mascarene types, together with two peculiar genera-Oxynotus belonging to the Campephagidre or caterpillar-catchers, a family abundant in the old-world tropir.s; and a dove, Trocazza, forming a peculiar subgenus. The origin of these birds offers no difficulty, looking at the position of the islands and of the surroundmg shoals and islets. Extinct Birds.-These three islands are, however, pre-eminently remarkable as being the home of .a group of large ground-birds, quite incapable of flight, and altogether unlike anything found elsewhere on the globe; and which, though once very abundant, have become totally extinct within the last two hundred years. Ths:~t known of these birds is the dodo, which inhabited Mauritl'us; while allied species certainly lived in Bourbon and Rodriguez, abundant remains of the species of the latter island -the "solitaire," having been discovered, corresponding with the figure and description given of it by Legouat, who resided in Rodriguez in 1692. These birds constitute a distinct family, Dididre, allied to the pigeons but very isolated. They were quite helpless, and were rapidly exterminated when man introduced dogs, pigs, and cats into the islands, and himself sought them for foofl. The fact that such perfectly defenceless creatures survived in great abundance to a quite recent period in these three islands only, while there is no evidence of their ever having inhabited any other countries whatever, is itself almost demonstrative that Mauritius, Bourbon, and Rodriguez are very ancient but truly oceanic islands. From what we know of the general similarity of Miocene birds to living genera and families, it seems clear that the origin of so remarkable a type as the dodos must date back to early Tertiary times. If we suppose some ancestral ground-feeding pigeon of large size to have |