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In the same way the Galapagos isles, Australia, and the isLin^Is of the Eastern 

 Archipelago have, more or less, faunas peculiar to each. It should be noticed 

 with reference to island faunas that the species inhabiting them are nearly always 

 allied to those which inhabit the nearest mainland. 



Glancing now at other portions of the world which are to a preat extent 

 continuous ; we find no very noticeable breaks in specific forms, nor any sudden 

 appearances of numerous new species, but that gradually one by one the species 

 give way to other species. This is especially striking while travelling north or 

 south, but is also observable, though in a much less degree, going east or west. 

 This is, of course, easily comprehended, as we know that latitude has a far 

 greater effect upon climate than longitude. 



It is also remarkable that as we approach the poles, we find that the same 

 species have frequently a very wide lateral range. This, of course, is more 

 observable in the case of the north pole than the south pole ; but aquatic 

 animals such as seals and penguins are found to prove the rule in the south. 



It should be carefully observed in studying the facts of distribution that the 

 same conditions of life, that is the same climate, same kind of food, &c., do not 

 at all ensure the presence of the same species of animals. 



Thus the climate and conditions of life of the tropical regions of America 

 and Africa are very similar, but the natural productions are wholly dissimilar. 

 Also the same may be said of Africa and Madagascar ; and perhaps the most 

 striking case of all is that of the islands of the Malayan Archipelago. The researches 

 of Mr. A. Wallace have brought to light the interesting character of the faunas of 

 these isles, and the great peculiarity of their distribution. 



He found the greatest contrast between the faunas of some of the islands 

 though only separated by a narrow strait. Thus between the islands of BaU and 

 Lomboc the strait is only 15 mUes wide, and yet these two islands have hardly a 

 mammal or bird in common. In Bali are fovmd woodpeckers, fruit thrushes, 

 and other birds belonging to Asia ; in Lomboc none of these are known, but In 

 their place cockatoos, honey-suckers, and brush turkies, which are all unknown 

 west of Lomboc, and are characteristic features of the Australian Fauna. In the 

 same way a striking difference is observable between the faunas of Borneo and 

 the Celebes, which are divided by the Macassar Straits. In the former are found 

 the large apes and monkeys of many kinds, wild cats, deer, otters, and squirrels ; 

 in the latter the cuscus, wild i>igs, and deer, which latter Mr. 'Wallace says have 

 been probably introduced. 



These facts strike one as most incomprehensible until it is known that the 

 seas which separate the Malayan Peninsula, Sumatra, Java, and Bali, are 

 comparatively shallow seas, rarely exceeding 40 fathoms in depth, whereas the 

 straits between BaU and Lomboc are very deep, as are also the Macassar Straits 

 between Borneo and Celebes. 



As all this region is highly volcanic with the exception of Borneo and New 

 Guinea, it is highly probable that at some period or other the islands of Sumatra, 

 Ja7a, and BaU, were severed from the main land, bearing with them of course 



