168 STUDIES IN LIFE AND SENSE. 



certain peculiar birds ; they are rich in peculiar fishes, and probably 

 in mosses of special kinds as well. But whilst these peculiarities 

 point to the existence of conditions which favour specialisation of 

 form, they do not in any sense oppose the idea strengthened into 

 absolute fact by all the considerations of geology and biology 

 namely, that at no remote date, but " recently " in a geological sense, 

 the " land of the free" itself had no special identity of its own, and 

 that all its future individuality was merged in its continuity with the 

 great continental area around. 



A brief reference to the peculiarities of Madagascar and New 

 Zealand may serve to conclude our reflections on islands and 

 detached land areas, as illustrative of the geological factors which 

 regulate the distribution of life on the earth's surface. The 

 peculiarities of New Zealand as a biological province have already 

 been discussed. Its want of native mammals and snakes, its single 

 frog, its peculiar lizard, and its living and extinct wingless birds, as 

 well as certain characters of its plant-life, mark it out as especially 

 peculiar. No less specialised and peculiar, on the other hand, is 

 Madagascar, the zoology of which has likewise been described. 

 The differences of its animals from those of the African continent ; 

 its peculiar lemurs ; its special insectivora and carnivora, and 

 rodents ; and its other biological features, render this great island a 

 highly specialised part of the world's surface. New Zealand and 

 Madagascar stand out prominently before us as examples of 

 " ancient continental islands." That " once upon a time " they 

 formed part of a continental area, no one may doubt ; but that 

 their separation has been so remote as well-nigh to justify the 

 appellation of " oceanic " islands, is also a logical deduction from 

 their biological history. In Madagascar and New Zealand are 

 beheld, in a word, the effects of isolation, which, depending in 

 turn upon geological changes and the submergence of land, gives 

 to the latter agencies their great power in modifying the life of the 

 globe. " Such islands," says Mr. Wallace, " preserve to us the 

 record of a bygone world of a period when many of the higher 

 types had not yet come into existence, and when the distribution 

 of others was very different from what prevails at the present day." 

 It is in islands such as Madagascar and New Zealand, that we see 

 preserved to us the remnants of a fauna that may once have been 

 of world-wide extent. Mr. Wallace, again, remarks that " A 

 partial subsidence will have led to the extinction of some of the 

 types that were originally preserved, and may leave the ancient 

 fauna in a very fragmentary state ; while subsequent elevations 

 may have brought it so near to the continent that some immigration, 

 even of mammalia, may have taken place. If these elevations and 

 subsidences occurred several times over, though never to such an 



