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 22 Serpicula differs from Myriophyllum in having only half the number of stamina in the male flower, and in its unilocular four-seeded ovarium.

Hippuris, though retaining the habit of Myriophyllum, yet having a monandrous hermaphrodite flower without petals, and a single-seeded ovarium, is less certainly reducible to this order: and it may appear still more paradoxical to unite with it Callitriche, in which, however, I am inclined to consider what authors have denominated petals as rather analogous to the bracteæ in the female flower of Myriophyllum and Serpicula, and to both these genera Callitriche in the structure of its pistillum, and even in habit, very nearly approaches.

The Australian genera of this order are Haloragis, Meionectes, Myriophyllum, and Callitriche.

Of Haloragis, many new species have been observed in Terra Australis, in every part of which this genus is found, most abundantly, however, at both extremities of the principal parallel.

That Gonocarpus really belongs to the same genus, I am satisfied from an examination of original specimens sent by Thunberg himself, to Sir Joseph Banks, for in these I find not only petals, but eight stamina and a quadrilocular ovarium.

LEGUMINOSÆ. This extensive tribe may be considered as a class divisible into at least three orders, to 551] which proper names should be given. Of the whole class about 2000 species are at present published, and in Terra Australis, where this is the most numerous family, considerably more than 400 species have already been observed.

One of the three orders of Leguminosæ which is here for the first time proposed may be named. It consists of the Linnean Mimosa, recently subdivided by Willdenow into five genera, along with Adenanthera and Prosopis.