CHAP, X.] THE PALZZARCTIC REGION. 181 
tions of convenience, dependent on custom and on the more or 
less perfect knowledge we possess of some of the intervening 
countries. 
Zoological Characteristics of the Palearctic Region.—The Pale- 
arctic region has representatives of thirty-five families of 
mamumalia, fifty-five of birds, twenty-five of reptiles, nine of 
amphibia, and thirteen of freshwater fishes. Comparing it with 
the only other wholly temperate region, the Nearctic, we find a 
much greater variety of types of mammalia and birds. This 
may be due in part to its greater area, but more, probably, 
to its southern boundary being conterminous for an enormous 
distance with two tropical regions, the Ethiopean and Oriental ; 
whereas the Nearctic has a comparatively short southern bound- 
ary conterminous with the Neotropical region only. This is so 
very important a difference, that it is rather a matter of surprise 
that the two north temperate regions should not be more unequal 
in the number of their higher vertebrate forms, than they 
actually are. 
It is also to the interblending of the Palearctic with the two 
adjacent tropical regions, that we must attribute its possession 
of so few peculiar family groups. These are only three; two 
of reptiles, Trogonophidw and Ophiomoride, and one of fishes, 
Comephoride. The number of peculiar genera is, however, con- 
siderable, as the following enumeration will show. 
Mammalia—tThe monkey of Gibraltar and North Africa, and 
an allied species found in Japan, are now considered to belong 
to the extensive eastern genus Macacus. The former, however, 
is peculiar in the entire absence of the tail, and has by many 
naturalists, been held to form a distinct genus, Jnwus, confined 
to the Palearctic region. 
Of bats there are one or two genera (Barbastellus, Plecotus) 
which seem to be mainly or wholly Palearctic, but the classifi- 
cation of these animals is in such an unsettled state that the 
distribution of the genera is of little importance. 
In the next order, Insectivora, we have almost the entire 
family of the Moles confined to the region. TZalpa just enters 
Northern India ; and Urotrichus is common to Japan and North- 
