Page:A Voyage to Terra Australis Volume 2.djvu/578

564 related to Rubiaceæ and Gentianeæ; the former appearing to differ chiefly in its remarkable stipulæ, the latter in its minute Embryo. If these characters be admitted, certain New Holland genera which I have placed with Gentianeæ will either be transferred to Rubiaceæ, or, as I have formerly proposed, may with some others, constitute a family intermediate to Rubiaceæ and Apocineæ.

This order or section, which may be named, will consist of Logania, Geniostoma, (from which Anasser of Jussieu is not distinct), Usteria, Gærtnera of Lamarck , Pagamea of Aublet, and, perhaps, Fagræa. Of these, the only New Holland genus is Logania, the greater part of whose species are found in the principal parallel. In this genus, which admits, however, of subdivision, the importance of stipulation seems to be entirely lost, for it contains species agreeing in this respect with Rubiaceæ, others in which the stipulæ are lateral and distinct, and one species, at least, in which they are entirely wanting.

There is an evident affinity between certain species of Logania and Mitrasacme, which I had therefore placed in Gentianeæ. Mitrasacme is very general in Terra Australis, but its maximum is within the tropic: it is not absolutely confined to New Holland, for I have observed in the Sherardian Herbarium two species collected at Cheusan, by Mr. Cunningham.

Among the true Apocineæ of New Holland, which are chiefly found within the tropic, the most remarkable genus is Alyxia, in which the albumen and embryo agree with those of the very different family Annonaceæ.

ASCLEPIADEÆ. These plants differ from Apocineæ, solely in the peculiar structure of their genitalia, a character, however, which appears to me, fully sufficient to justify their separation. They are not very numerous in New Holland, where they are found chiefly within the tropic, and I have not observed any plant of the order in that country in a higher latitude than 34° S.

EPACRIDEÆ. The abundance of this family in Terra Australis