d an
influence on the _habitations_ of plants."

_Stations and habitations of plants._--As I shall frequently have
occasion to speak of the _stations_ and _habitations_ of plants in the
technical sense in which the terms are used in the above passage, I may
remind the geologist that station indicates the peculiar nature of the
locality where each species is accustomed to grow, and has reference to
climate, soil, humidity, light, elevation above the sea, and other
analogous circumstances; whereas, by habitation is meant a general
indication of the country where a plant grows wild. Thus the _station_
of a plant may be a salt-marsh, a hill-side, the bed of the sea, or a
stagnant pool. Its _habitation_ may be Europe, North America, or New
Holland, between the tropics. The study of stations has been styled the
topography, that of habitations the geography, of botany. The terms thus
defined, express each a distinct class of ideas, which have been often
confounded together, and which are equally applicable in zoology.

In farther illustration of the principle above alluded to, that
difference of longitude, independently of any influence of temperature,
is accompanied by a great, and sometimes a complete, diversity in the
species of plants, De Candolle observes, that, out of 2891 species of
phaenogamous plants described by Pursh, in the United States, there are
only 385 which are found in northern or temperate Europe. MM. Humboldt
and Bonpland, in all their travels through equinoctial America, found
only twenty-four species (these being all Cyperaceae and Gramineae) common
to America and any part of the Old World. They collected, it is true,
chiefly on the mountains, or the proportion would have been larger; for
Dr. J. Hooker informs me that many tropical plants of the New World are
identical with African species. Nevertheless, the general discordance of
these Floras is very striking. On comparing New Holland with Europe, Mr.
Brown ascertained that, out of 4100 species, discovered in Australia,
there were only 166 common to Europe, and of this small number there
were some few which may have been transported thither by man. Almost all
of the 166 species were cryptogamic, and the rest consist, in nearly
every case, of phaenogamous plants which also inhabit intervening
regions.

But what is still more remarkable, in the more widely separated parts of
the ancient continent, notwithstanding the existence of an uninterrupted
land-