My investigation of the natural productions of Australia induces me to believe, that at some remote period that country was divided into at least two portions, since, with a few exceptions, I find the species inhabiting the same latitudes of its eastern and western divisions differing from, but representing each other. Some writers, Captain Sturt and Mr. Jukes, _e.g._ are of opinion that its subdivision was even greater, and that the sandy deserts now met with in the interior were formerly the beds of the seas that flowed between the archipelago of islands of which they suppose it to have been composed. In a valuable paper by Mr. Jukes, entitled ‘Notes on the Geology of the Coasts of Australia,’ read at the meeting of the Geological Society on the 17th of November 1847, that gentleman stated, that “The eastern coast is occupied by a great range of high land, appearing like a continuous chain of mountains when seen from the sea, and rising in several places to 5000 feet or more above the sea-level. This chain has an axis of granite, with occasional large masses of greenstone, basalt and other igneous rocks. It is flanked on both sides by thick beds of palæozoic formations, chiefly sandstone, but also containing limestone and coal. In the northern portion of the chain Dr. Leichardt found similar formations—and especially trap and granite near the Burdekin river. In the Port Phillip district there are similar igneous rocks, and on the coast tertiary formations resting on the edges of upturned palæozoic beds. In West Australia, the Darling range consists of granite below, covered by metamorphic rocks; and between it and the sea is a plain composed of tertiary beds. In the colony of North Australia there is a great sandstone plateau, rising about 1800 feet above the sea, and probably of palæozoic age; whilst on the immediate shore and round the Gulf of Carpentaria are beds supposed to belong to the tertiary period. Similar formations constitute the substratum of the central desert; in which Captain Sturt was compelled to turn back, when half-way to the Gulf of Carpentaria, from the southern coast. Hence these tertiary rocks are probably continuous through the whole centre of the island, and during the tertiary period all this portion of the country was submerged, whilst the high lands on the coast rose like four groups of islands from the shallow sea.”—_Athenæum_, _Nov. 24, 1847_. Whichever of these opinions be the correct one, we certainly find the natural productions of all these portions of the country composed of precisely the same types, the generality of which differ entirely from those of the islands of the Indian Archipelago on the one hand, and of New Zealand and Polynesia on the other.