n to the
principal parallel, and the extent of the peculiar families may now be
stated as much greater at or near its western, than at its eastern
extremity.

With the vegetation of the extra-tropical interior of Australia, we are
now in some degree acquainted, chiefly from the collections formed by the
late Mr. Allan Cunningham, and Charles Fraser, in Oxley's two expeditions
from Port Jackson into the western interior, in 1817 and 1818; from
Captain Sturt's early expeditions, in which the rivers Darling,
Murrumbidgee, and Murray, were discovered; from those of Sir Thomas
Mitchell, who never failed to form extensive collections of plants of the
regions he visited; and lastly, from Captain Sturt's present collection.

The whole number of plants collected in these various expeditions, may be
estimated at about 700 or 750 species; and the general character of the
vegetation, especially of the extensive sterile regions, very nearly
resembles that of the heads of the two great inlets of the south coast,
particularly that of Spencer's Gulf; the same or a still greater
diminution of the characteristic tribes of the general Australian Flora
being observable. Of these characteristic tribes, hardly any considerable
proportion is found, except of Eucalyptus, and even that genus seems to
be much reduced in the number of species; of the leafless Acaciae, which
appear to exist in nearly their usual proportion; and of Callitris and
Casuarina. The extensive families of Epacrideae, Stylideae, Restiaceae,
and the tribe of Decandrous Papilionaceae, hardly exist, and the still
more characteristic and extensive family of Proteaceae is reduced to a
few species of Grevillea, Hakea, and Persoonia.

Nor are there any extensive families peculiar to these regions; the only
characteristic tribes being that small section of aphyllous, or nearly
aphyllous Cassiae, which I have particularly adverted to in my account of
some of the species belonging to Captain Sturt's collection; and several
genera of Myoporinae, particularly Eremophila and Stenochilus. Both these
tribes appear to be confined to the interior, or to the two great gulfs
of the South coast, which may be termed the outlets or direct
continuation of the southern interior; several of the species observed at
the head of Spencer's Gulf, also existing in nearly the same meridian,
several degrees to the northward. It is not a little remarkable that
nearly the same general character of vegetat