EVIDENCES FROM GEOGRAPHIC DISTRIBUTION 



i8i 



Moreover, these i6 land-birds constitute no less than lo peculiar 

 genera, and even one peculiar family of five genera. This is an amount 

 of peculiarity far exceeding that of any other islands, and, of course, 

 corresponds with the great isolation of this archipelago. The only 

 other animals which have here been carefully studied are the land- 

 shells, and these tell the same story as the birds. For there are no less 

 than 400 species which are all, without any exception, pecuhar; while 

 about three-quarters of them go to constitute peculiar genera. 

 Again, of the plants, 620 species are believed to be endemic; and of 

 these 377 are pecuhar, yieldmg no less than 39 pecuUar genera. 



THE FAUNA OF CONTINENTAL ISLANDS — MADAGASCAR AND NEW ZEALAND' 



A. R. WALLACE 



The two exceptions just referred to are Madagascar and New 

 Zealand, and all the evidence goes to show that in these cases the land 

 connection with the nearest continental area was very remote in time. 

 The extraordinary isolation of the productions of Madagascar — almost 

 all the most characteristic forms of mammalia, birds, and reptiles of 

 Africa being absent from it — renders it certain that it must have been 

 separated from that continent very early in the Tertiary, if not as far 

 back as the latter part of the Secondary period; and this extreme 

 antiquity is indicated by a depth of considerably more than a thousand 

 fathoms in the Mozambique Channel, though this deep portion is less 

 than a hundred miles wide between the Comoro Islands and the main- 

 land. Madagascar is the only island on the globe with a fairly rich 

 mammalian fauna which is separated from a continent by a depth 

 greater than a thousand fathoms; and no other island presents so 

 many pecuUarities in these animals, or has preserved so many lowly 

 organised and archaic forms. The exceptional character of its pro- 

 ductions agrees exactly with its exceptional isolation by means of a 

 very deep arm of the sea. 



New Zealand possesses no known mammals and only a single 

 species of batrachian; but its geological structure is perfectly conti- 

 nental. There is also much evidence that it does possess one mammal, 

 although no specimens have been yet obtained. Its reptiles and birds 

 are highly peculiar and more numerous than in any truly oceanic 

 island. Now the sea which directly separates New Zealand from 

 Australia is more than 2,000 fathoms deep, but in a north-west direc- 



' From A. R. Wallace, Darwinism (copyright 1889). Used by special permis- 

 sion of the publishers, The Macmillan Company. 



