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12 The greater part of the order exists in the principal parallel, very few species have been observed within the tropic, and one only in Van Diemen's Island.

Lasiopetalum, the most extensive genus of the family, was established by Dr. Smith, who considered it to belong to Ericeæ. Ventenat, taking a different view of its structure, has assigned some plausible reasons for referring it to Rhamneæ. From both these orders it appears to me sufficiently distinct, and it is certainly more nearly related to the genera with which I have placed it.

DILLENIACEÆ. It was first, I believe, proposed by Mr. Salisbury to separate Dillenia, Wormia, Hibbertia, and Candollea from the Magnoliæ of Jussieu, and to form them into a distinct order, which he has called Dilleneæ. It is remarkable that Decandolle, who has adopted this order, should also limit it to these genera, Jussieu having previously suggested the separation of Dillenia from Magnoliæ and its combination with Tetracera and Curatella, genera which certainly belong to Dilleniaceæ, as do also Pleurandra of Labillardière and Hemistemma of Du Petit Thouars.

The Dilleniaceæ appear to be more abundant in Terra Australis than in any other part of the world, nearly seventy Australian species having already been observed; most of these belong to Hibbertia and Pleurandra, both of which are very generally diffused, their maximum, however, is in the principal parallel, to the western extremity of which Candollea seems to be limited. Hemistemma, Wormia, 542] and an unpublished genus remarkable for its thickened filaments and flat leafless stems, are found only within the tropic. The remaining genera of the order have not yet been observed in New Holland.