The one discovered on the North-west Coast, and allied to H.angustifolium of Mr.
Brown; the other proving also new, but approaching in character the doubtful species, H.leschenaultii of Decandolle, and was discovered upon Rottnest Island, off the western coast of the continent, and is the first certain species of the genus, that is not limited to a tropical existence.
In addition to what has been advanced in respect to certain natural orders that appear in the Herbarium, formed under the stated circumstances, a slight mention might be made of other detached genera, or families sparingly observed on these coasts, that were more particularly investigated during the progress of the late voyages; but as these several plants form portions of orders so extremely limited, and in themselves presenting nothing remarkable in their internal structure, or external habit, a few remarks on a general comparison of the vegetation of the North-west Coast, with the other shores of Terra Australis, will conclude this notice.
It is very necessary to premise, that the plants observed and collected upon the North-west Coast, during the late voyages, are not to be considered as even a distant approach to an entire Flora of that extensive line of shore; since the long-established droughts of the seasons (as already remarked) in which the greater part of that coast was visited, had wholly destroyed plants of annual duration, with most of the Gramineae, and had indeed generally affected the mass of its herbaceous vegetation.

The collections, therefore, can simply be viewed as a gleaning, affording such general outlines of characteristic feature, as will enable the botanist to trace its affinity to the more minutely defined vegetation of the other equinoctial shores of the continent, as well as perceive its general, and, in some instances, almost total want of relation to the botany of other parts, in the more temperate or higher latitudes, where certain striking peculiarities of the Australian Flora more particularly exist.
Upon a general comparison of those collections that were thus formed on the North-west Coast, with the plants of the North and East Coasts, aided also by some few observations made during the voyages, it appears that (with the exception of Gompholobium, Boronia, Kennedia, and one or two unpublished species not referred to any family) the genera (of which several are proper to India) are the same, although the species are very distinct upon the several coasts.
Notwithstanding an identity of genera has been remarked upon their opposite shores, there are, nevertheless, certain others, frequent upon the East Coast, that appear wholly wanting on the north-western shores: of these, the existence of some, even in the tropical parts of New South Wales, seems governed by the primary formation of the coast, its mountainous structure, and consequent permanency of moisture in a greater or less degree; namely, almost all the genera of Filices, the parasitical Orchideae, Piper, Dracontium and Calladium (genera of Aroideae) Commelina and Aneilema, Calamus and Seaforthia, Hellenia a solitary Australian genus of Scitamineae, some genera of Rubiaceae, particularly Psychotria and Coffea, certain genera of Asphodeleae, as Cordyline, and a genus allied to it, whose fructification is at length obtained, a solitary plant of Melastomeae, and an individual Nymphea.
Other genera also, but little influenced by those local circumstances of situation on the East Coast, that are excluded from the opposite shores, are Leucopogon (the only equinoctial genus of Epacrideae observed during the late voyages) the families Bignoniaceae, Jasmineae, the genus Erythrina, and of Coniferae, Araucaria of Norfolk Island.

This absence of several orders of plants on the north-western shores, existing in New South Wales, or opposite coast, as well as the consideration (at the same time) of the evident causes of such a disparity of species on the former coast, would suggest the opinion, that such plants alone of other parts of the continent are indigenous to the North-west Coast, as are capable of sustaining themselves in a soil subjected to seasons of protracted parching droughts.

This may apply to some species upon that coast, but it cannot be reduced to a general conclusion; for, on the one hand, it is singular so few of the plants of the South and South-west Coasts, and particularly that none other of their genera of Proteaceae (than those already mentioned) found altogether in an arid soil, should have been discovered throughout any part of its extensive shore; whilst, on the other hand, at a peculiar structure of a small and limited portion of that coast, in the vicinity of York Sound, a sufficiency of shade was observed to be actually produced by the unusually broken character of the country, to favour the nourishment and growth of certain plants alone to be seen beneath the shade of dense forests.

These species were Myristica insipida, discovered by Mr.Brown, on one of the Prince of Wales group of islands on the North Coast; Cryptocarya triplinervis, Brown; bearing ripe fruit, Abroma fastuosa; and an undescribed Eugenia.
Although the several genera of plants lately observed on the north-western shores are also frequent in other equinoctial parts of the continent, there is, among the many species which are absolutely proper to that coast, a Capparis of such extraordinary habit, as to form a feature in the landscape of a limited extent of its shores, in the enormous bulk of its stem and general ramification, bearing a striking analogy to the Adansonia of the west coast of Africa.
The results of such observations on the vegetation as could only be made in a general way, at parts approaching each extreme of the North-west Coast, show their little affinity to each other; for the northern extremity partakes more fully of that feature of the line of coast contiguous to it, which (as already remarked) extends along the north-western shores, declines materially at, and in the vicinity of their southern limits, where the characteristic vegetation of the south, and perhaps the west, coasts has more particularly been found.