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Show 458 DR. F. B. WHITE ON THE [May 7, wood-frequenting-Anchastus, Anobium, the 17 genera of Cossonidee, Nesiotes, &c. Thus 16 out of the 25 peculiar genera, and nearly 80, at least, out of the 129 peculiar species, live in wood at some period of their existence. The Anthribidee, of which 26 species occur in St. Helena, are not wood-borers, although probably lignivorous as larvae, but cling rather tenaciously to foliage, dead wood, &c. ; and they, as well as most of the remaining Coleoptera as well as the species of the other groups which are also attached to plants, must be specially liable to transportation in or about drift-wood, &c. In the case of winged species the winds, of course, would assist in the work. But it is unnecessary to pursue this subject any further, save to mention that though most of the plant-frequenting beetles are attached to some one or other of the peculiar plants, it by no means follows that their ancestors were so restricted ; for, as observed by Mr. Wollaston, some at the present day devour with apparently equal relish, the native arborescent Compositae and the introduced Coniferse. Nor is it necessary to suppose that they were introduced with the tree Compositae, because it is probable that the progenitors of the latter were not arborescent when they arrived in the island, but that that condition was gradually evolved1. Some of the Cossonidee are quite content with the pithy stems of thistles & c , though the family is essentially wood-loving. It is also worth while noting the extreme paucity of that section of the Coleoptera known as the Phytophaga, which seems to show not only that the lignivorous beetles had more facilities of transport than those that merely fed upon the leaves of plants, but that, as Mr. Wollaston remarks, the early flora of St. Helena was essentially a woody one. Now that the forest has vanished, and though the greater part of the island is suited for the Phytophaga, yet the number of species remains the same-showing, I think, that colonization (apart from that brought about by man's unintentional agency) is not now going on. A word now as to the flora. The aboriginal plants have, as has been already said, most affinity with the flora of Southern extra-tropical Africa. This affinity can surely only arise from a common origin; and if, as I have attempted to prove, the origin of the fauna is Palaearctic, it seems reasonable to suppose that the origin of the flora is the same, and that the same agencies which brought its fauna to St. Helena brought its flora also. Without going into details of the South-African flora (for which, indeed, I have not the materials), I may mention that there are one or two genera of plants common to it and to St. Helena which are strongly suggestive of a Palaearctic origin and dispersion by the influence of a glacial epoch:- for example, Slum, which has an endemic representative in St. Helena; the very characteristic Cape genus Pelargonium, which has a straggler in Syria (where, be it noted, the endemic St.-Helenian coleopterous genus Haplothorax has, according to Lacordaire, its nearest allies) ; and others. 1 Darwin, 1. c. p, 350. |