452 Mr. Wallace on the Geographical Distribution of Birds. 
wants with the population; whereas, even in the most remote 
districts of South America, one is always in contact with men of 
European race and feelings, and with at least a remnant of the 
usages and wants of European civilization. South America too 
possesses a physical superiority to every other region, which would 
lead us to expect a vast richness in its natural productions. No¬ 
where else in the Tropics are such vast and fertile alluvial plains, 
such mighty forests, such gigantic rivers, such an extensive and 
lofty range of mountains. There is no such compact mass of 
intertropical land as South America. There is no mountain range 
hut the Andes, both sides of which are in the Tropics. This 
long succession of temperate plateaux, together with the southern 
extremity of South America, adds immensely to the diversity of 
its fauna, combining in fact all the varied physical features and 
stations of the Old World in a space of barely one-fifth its ex¬ 
tent. It thus happens that in many cases the natural produc¬ 
tions of South America will bear comparison not only with any 
one of the other regions, but with all the rest of the world, espe¬ 
cially if we leave out Australia as an altogether peculiar region, 
having no more connexion with the old than with the new con¬ 
tinent. 
There is perhaps no fact connected with geographical dis¬ 
tribution more extraordinary, and at first sight inexplicable, 
than the division of such an apparently homogeneous tract as 
the Indian Archipelago between two provinces which have less 
in common than any other two upon the earth. To the geo¬ 
grapher and geologist, there is absolutely nothing to mark the 
division between the two regions. 
Borneo differs more from Java than does the former from 
Celebes, or the latter from Timor, The Philippines strikingly 
resemble the Moluccas in their physical features; Borneo has 
much resemblance to New Guinea, yet their zoological produc¬ 
tions differ greatly. Between the Indian and Australian zoo¬ 
logical regions, as above defined, I believe there is absolutely no 
true transition—that is, no species are common to the two, 
which we cannot easily account for by the various accidents and 
migrations which in the course of ages must have tended to 
mingle the productions of islands so close to each other. I believe 
