ies mainly confined to the Himalayas, but with a
few straggling species in the Malay countries and the mountains of China;
the Pteroptochidae, large wren-like birds, consisting of eight genera and
nineteen species, almost entirely confined to temperate South America and
{30} the Andes; and the birds-of-paradise, consisting of nineteen or twenty
genera and about thirty-five species, almost all inhabitants of New Guinea
and the immediately surrounding islands, while a few, doubtfully belonging
to the family, extend to East Australia. Among reptiles the most striking
case of restriction is that of the rough-tailed burrowing snakes
(Uropeltidae), the five genera and eighteen species being strictly confined
to Ceylon and the southern parts of the Indian Peninsula.

_The Distribution of Orders._--When we pass to the larger groups, termed
orders, comprising several families, we find comparatively few cases of
restriction and many of worldwide distribution; and the families of which
they are composed are strictly comparable to the genera of which families
are composed, inasmuch as they present examples of overlapping, or
conterminous, or isolated areas, though the latter are comparatively rare.
Among mammalia the Insectivora offer the best example of an order, several
of whose families inhabit areas more or less isolated from the rest; while
the Marsupialia have six families in Australia, and one, the opossums, far
off in America.

Perhaps, more important is the limitation of some entire orders to certain
well-defined portions of the globe. Thus the Proboscidea, comprising the
single family and genus of the elephants, and the Hyracoidea, that of the
Hyrax or Syrian coney, are confined to parts of Africa and Asia; the
Marsupials to Australia and America; and the Monotremata, the lowest of all
mammals--comprising the duck-billed Platypus and the spiny Echidna, to
Australia and New Guinea. Among birds the Struthiones or ostrich tribe are
almost confined to the three Southern continents, South America, Africa and
Australia; and among Amphibia the tailed Batrachia--the newts and
salamanders--are similarly restricted to the northern hemisphere.

These various facts will receive their explanation in a future chapter.

* * * * *

[Illustration]

{31}

CHAPTER III

CLASSIFICATION OF THE FACTS OF DISTRIBUTION.--ZOOLOGICAL REGIONS

The Geographical Divisions of the Globe do not correspond to Z