REVIEWS. 
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should hardly have ventured to treat the whole subject had it not been for 
the kind encouragement of Mr. Darwin and Professor Newton, who, about 
six years ago, both suggested that I should undertake the task. I accord- 
ingly set to work, but soon became discouraged by the great dearth of 
materials in many groups, the absence of general systematic works, and the 
excessive confusion that pervaded the classification. Neither was it easy to 
decide on any satisfactory method of treating the subject. During the next 
two years, however, several important catalogues and systematic treatises 
appeared, which induced me to resume my work, and during the last three 
years it has occupied a large portion of my time.” 
And what, the general reader will probably ask, has the author of the 
work attempted ? We shall endeavour to explain. Animal life exists in 
almost every portion of the globe ; indeed, for convenience, we may assume 
that on every portion of the earth animal life is apparent. But we find as 
we travel through, suppose the forests of Brazil, or the regions of Upper 
India, or in the Arctic provinces, or again in Australia, a very different set 
of animals. Thus in one we find all the creatures have, more or less, marsu- 
pial pouches, as the kangaroo ; in another we find the old-world apes ; in a 
third we find elephants, and so on. Then again in point of time — that is, 
suppose a million of years — we find similarly a peculiarity of distribution of 
animal existence. For example, we find one type of animals succeeding 
another as we pass from the older to the more recent fossiliferous deposits. 
Now in both these cases it is of importance to find out how it happens that 
such different forms of life came in these localities, both of space or of 
surface, and of depth. Of course, if you took the view that every animal 
was separately created, there would be at once an end to the whole discus- 
sion ; for then you would have taken it for granted, not that the animal cf 
any particular locality arrived there ages ago from elsewhere, but that it 
was created on the spot. That would be an exceedingly singular view ; 
and, unfortunately for his convenience, the scientific man must give it up at 
once. Then for him comes the question, How did these several races extend 
from one part of the world to another P Why, for example, should we find 
fossil in this country animals the same as those now living in Australia P 
It is to this excessively difficult task that Mr. Wallace has partly devoted 
his attention, though of course he has had in the first instance to en- 
deavour to arrange all the animals which are on the globe into a series of 
groups, so as to have those that are closely related to each other as to dis- 
tribution as much together as possible. And Mr. Wallace has discussed 
the various schemes that have been suggested by different writers, and he 
has come to the conclusion that there are — as long since proposed by Mr. 
Sclater — six regions into which the world may be divided. These are 
(1) Palceartic, which includes North Europe, Mediterranean, Siberia, and 
Japan. (2) Ethiopian, which comprises East, West, and South Africa and 
Madagascar. (8) Oriental, which includes Ilindostan, Ceylon, Indo-China, 
and Indo-Malaya. (4) Australian , including Austra-Malaya, Australia, 
Polynesia, and New Zealand. (5) Neotropical, including Chili, Brazil, 
Mexico, and Antilles; and (6) Nearctic, comprehending California, the Bocky 
Mountains, the Alleghanies, and Canada. Now taking these great groups 
as the primary division of the animal world, the author traces every genus 
