Australia between the 33rd and 35th parallels of south latitude, but that at the eastern and western extremities of these parallels not one species is common to both, and that certain genera also are almost entirely confined to these spots. The number of species common to Australia and Europe are only 166 out of 4100, and probably some of these have been conveyed thither by the colonists; but the greater part of that continent is still unexplored. However, this proportion exceeds what has hitherto been observed in southern Africa, and, from what has been already stated, the proportion of European species in Equinoctial America is still less. Islands partake of the vegetation of the nearest continents; but, when very remote from land, their floras are altogether peculiar. The Aleutian Islands, extending between Asia and America, partake of the vegetation of the northern parts of both continents, and may have served as a chain of communication. In Madeira and Teneriffe, the plants of Portugal, Spain, the Azores, and of the northern coast of Africa, are found; and the Canaries contain a great number of plants belonging to the African coast. But each of these islands possesses a flora that exists nowhere else; and St. Helena, standing alone in the midst of the Atlantic Ocean, produces only two or three species of plants recognised as belonging to any other part of the world. It appears from the investigations of M. de Humboldt that between the tropics the plants, such as grasses and palms, which have only one seed-lobe, are to the tribe which have two seed-lobes, like most of the European species, in the proportion of one to four; in the temperate zones they are as one to six; and in the Arctic regions, where mosses and lichens, which form the lowest order of the vegetable creation, abound, the proportion is as one to two. Annuals with one and two seed-lobes, in the temperate zones, amount to one-sixth of the whole, omitting the cryptogamia (N. 218); in the torrid zone they scarcely form one-twentieth, and in Lapland one-thirtieth part. In approaching the equator the ligneous exceed the number of herbaceous plants; in America there are 120 different species of forest trees, whereas in the same latitudes in Europe only 34 are to be found.