Page:A Voyage to Terra Australis Volume 2.djvu/581

Natural Orders.] before the ripening of the seed: for previous to the complete developement of the Embryo the fluid albumen or liquor amnios equally exists in both orders; and although all the genera of Verbenaceæ have an Embryo whose radicule points towards the base of the fruit, yet many of them have pendulous seeds, and consequently a radicule remote from the umbilicus. Hence Avicennia, which I formerly annexed to Myoporinæ, should be restored to Verbenaceæ, with which also it much better agrees in habit.

Myoporinæ, with the exception of Bontia, a genus of æquinoctial America; and of two species of Myoporum found in the Sandwich Islands, has hitherto been observed only in the southern hemisphere, and yet neither in South Africa, nor in South America beyond the tropic. Its maximum is evidently in the principal parallel of Terra Australis, in every part of which it exists; in the more southern parts of New Holland, and even in Van Diemen's Island it is more frequent than within the tropic. The genus Myoporum is also found in New Zealand, Norfolk Island, New Caledonia, and the Society Islands.

PROTEACEÆ. I have formerly offered several observations both on the geographical distribution and on some of the more remarkable points of structure of this order of plants. I shall now therefore confine myself to a few of the most important facts on each of these subjects.

Proteaceæ are chiefly natives of the Southern hemisphere, in which they are most abundant in a parallel included between 32° and 35° lat. but they extend as far as 55° S. lat. The few species found in the Northern hemisphere occur within the tropic.

Upwards of 400 species of the order are at present known, more than half of these are natives of Terra Australis, where they form one of the most striking peculiarities of the vegetation. Nearly four-fifths of the Australian Proteaceæ belong to the principal parallel, in which, however, they are very unequally distributed: the number of species at its western extremity being to those of the eastern as about 2 to 1, and what is much more remarkable, the number even at the eastern extremity being to that of the middle of the parallel as at least 4 to 1. From the principal parallel the diminution of the order in number of species is nearly equal in both