or of a group, and so introduced a conception
which has become a permanent part of zooelogical science.

With regard to the number and limits of the zooelogical regions into
which the world may be divided, Huxley raised a number of problems
which have not yet reached a full solution. Mr. Sclater had divided
the world into six great regions: the Nearctic, including the
continent of North America, with an overlap into what is called South
America by geographers; the Palaearctic, comprising Europe and the
greater part of Asia; the Oriental, containing certain southern
portions of Asia, such as India south of the Himalayas and many of the
adjacent islands; the Ethiopian, including Africa, except north of
the Sahara, and Madagascar; the Australian, containing Australia and
New Zealand and some of the more southeastern of the islands of Malay;
the Neotropical, including South America. Huxley first called
attention to certain noteworthy resemblances between the Neotropical
and the Australian regions of Sclater, and held that a primary
division of the world was into _Arctogaea_, comprising the great land
masses of the Northern Hemisphere with a part of their extension
across the equator, and _Notogaea_, which contained Australia but not
New Zealand and South America. Although this acute suggestion has not
been generally accepted as a modification of Mr. Sclater's scheme, it
called attention in a striking fashion to some very remarkable
features in the distribution of animals. Subsequent writers have
considerably extended Huxley's conception of the similarities to be
found among the more southern land areas. They have pointed out that
the most striking idea of the distribution of land and water on the
surface of the globe is to be got by considering the globe alternately
from one pole and from the other. In the south, a clump of ice-bound
land, well within the Antarctic Circle, surrounds the pole. All else
is a wide domain of ocean broken only where tapering and isolated
tongues of land, South America, the Cape, Australia, lean down from
the great land masses of the north. On the other hand, all the great
land masses expand in the Northern Hemisphere, and shoulder one
another round the North Pole. America is separated from Asia only by
the shallowest and narrowest of straits; an elevation of a few fathoms
would unite Greenland with Europe. Science points definitely to some
part of the great northern land area as the centre of li