[ 235 ] X. On the Vegetation of the Galapagos Archipelago, as compared with that of some other Tropical Islands and of the Continent of Ama'ica. By Joseph Dalton Hooker, Esq^., M.D., F.R.S., F.L.S. <Sfc. S^c. Read December 1st and ISth, 184G. 1 HE Florula of the Galapagos Islands, which I recently had the honour of laying before this Society, was drawn up with the view of enabling me to discuss at length the geographical distribution of the plants contained in that singular Archipelago. As a field of observation, this group possesses the rare advantage of being one whose vegetation has never been interfered with by any aborigines of the human race ; and it is only very lately that the operations of man, or of animals introduced by his means, have disturbed the indigenous Flora, and that to a very limited extent only. It possesses the further singu-larity of containing a Flora differing by upwards of one-half its species from that of the rest of the globe, a peculiarity shared by no other tract of land of equal size, excepting perhaps the Sandwich group ; whilst only three out of the 123 new species, collected by various voyagers, have been previously described. Before commencing the study of the plants, I was assured of their being of a very novel character, especially from the masterly sketch of the unique zoology and the unequal dispersion of the species over the several islets com-posing this group given by Mr. Darwin, to whose comprehensive view of the natural history of the Galapagos this essay can be considered as supple-mentary only. The results of my examination have been, that the relation-ship of the Flora to that of the adjacent continent is a double one, the peculiar or new species being for the most part allied to plants of the cooler parts of America, or the uplands of the tropical latitudes, whilst the non-peculiar are the same as abound chiefly in the hot and damper regions, as the West Indian islands and the shores of the Gulf of Mexico; also that, as VOL. XX. 2 I
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