CHAP. IV.] ZOOLOGICAL REGIONS. 71 
are, for our present purpose, of much less importance. As a 
primary division the “ Arctic region” would be out of all pro- 
portion to the other six, whether as regards its few peculiar 
types or the limited number of forms and species actually in- 
habiting it; but it comes in well as a connecting link between 
two regions, where the peculiar forms of both are specially modi- 
fied; and is in this respect quite analogous to the great desert 
zone above referred to. 
I now proceed to characterize briefly the six regions adopted 
in the present work, together with the sub-regions into which 
they may be most conveniently and naturally divided, as shown 
in our general map. 
Palearctic Region—This very extensive region comprises all 
temperate Europe and Asia, from Iceland to Behring’s Straits and 
from the Azores to Japan. Its southern boundary is some- 
what indefinite, but it seems advisable to comprise in it all 
the extra-tropical part of the Sahara and Arabia, and all 
Persia, Cabul, and Beloochistan to the Indus. It comes down 
to a little below the upper limit of forests in the Himalayas, 
and includes the larger northern half of China, not quite so 
far down the coast as Amoy. It has been said that this 
region differs from the Oriental by negative characters only; a 
host of tropical families and genera being absent, while there is 
little or nothing but peculiar species to characterize it abso- 
lutely. This however is not true. The Palearctic region is well 
characterized by possessing 3 families. of vertebrata peculiar 
to it, as well as 35 peculiar genera of mammalia, and 57 
of birds, constituting about one-third of the total number it 
possesses. These are amply sufficient to characterize a region 
positively ; but we must also consider the absence of many im- 
portant groups of the Oriental, Ethiopian, and Nearctic regions ; 
and we shall then find, that taking positive and negative 
characters together, and making some allowance for the neces- 
sary poverty of a temperate as compared with tropical regions, 
the Palearctic is almost as strongly marked and well defined as 
any other. 
Sub-divisions of the Palearctic Region.—These are by no means 
