however, confine myself to a few remarks on the distribution of the most extensive genera.
Of Eucalyptus alone nealy 100 species have been already observed, most of these are trees, many of them of great and some of enormous dimensions. Eucalyptus globulus of Labillardiere and another species peculiar to the south end of Van Diemen's Island, not unfrequently attain the height of 160 feet, with a girth near the base of from 25 to 40 feet. In the colony of Port Jackson there are also several species of great size, but none equal to those of Van Diemen's Island: and no very large trees of this genus were seen either on the south coast or in the equinoctial part of New Holland. Mr. Caley has observed within the limits of the colony of Port Jackson nearly 50 species of Eucalyptus, most of which are distinguished, and have proper names applied to them, by the native inhabitants, who from differences in the colour, texture, and scaling of the bark, and in the ramification and general appearance of these trees, more readily distinguish them than botanists have as yet been able to do. Eucalyptus, although so generally spread over the whole of Terra Australis, and so abundant as to form at least four-fifths of its forests, is hardly found beyond this country. I am acquainted with one exception only, in an additional species which is said to be a native of Amboyna.
Next to Eucalyptus in number, is the beautiful genus Melaleuca, of which upwards of 30 Australian species have already been observed, exclusive of Tristania, Calothamnus, Beaufortia, and an unpublished genus which I separate from it. The maximum of Melaleuca exists in the principal parallel, but it declines less towards the south than within the tropic, where its species are chiefly of that section which gradually passes into Callistemon, a genus formed of those species of Metrosideros that have inflorescence similar to that of Melaleuca, and distinct elongated filaments. With the exception of two species of this section, namely, Melaleuca Leucadendron, and M. Cajeputi, the genus Melaleuca appears to be confined to Terra Australis.
Leptospermum, of which, nearly 30 Australian species have been observed, exists also in New Zealand and in the Moluccas. In Terra Australis its maximum is decidedly in the principal parallel, and like Melaleuca, it is much more abundant in the southern regions than within the tropic.
