Where there is so much unproductive surface the unavoidable dispersion of population renders good lines of communication more essentially necessary, and these must consist of roads, for there are neither navigable rivers nor in general the means of forming canals. This colony might thus extend northward to the tropic of Capricorn, westward to the 145th degree of east longitude, the southern portion having for boundaries the Darling, the Murray and the seacoast. Throughout the extensive territory thus bounded one-third, probably, consists of desert interior plains; one-fourth of land available for pasturage or cultivation; and the remainder of rocky mountain or impassable or unproductive country. Perhaps the greater portion of really good land within the whole extent will be found to the southward of the Murray, for there the country consists chiefly of trap, granite, or limestone. The amount of surface comprised in European kingdoms affords no criterion of what may be necessary for the growth of a new people in Australia. Extreme differences of soil, climate, and seasons may indeed be usefully reconciled and rendered available to one community there; but this must depend on ingenious adaptations aided by all the facilities man's art can supply in the free occupation of a very extensive region. Agricultural resources must ever be scanty and uncertain in a country where there is so little moisture to nourish vegetation. We have seen, from the state of the Darling where I last saw it, that all the surface water flowing from the vast territory west of the dividing range, and extending north and south between the Murray and the tropic, is insufficient to support the current of one small river. The country southward of the Murray is not so deficient in this respect for there the mountains are higher, the rocks more varied, and the soil consequently better; while the vast extent of open grassy downs seems just what was most necessary for the prosperity of the present colonists and the encouragement of a greater emigration from Europe. DESCRIPTION OF AUSTRALIA FELIX. Every variety of feature may be seen in these southern parts, from the lofty alpine region on the east, to the low grassy plains in which it terminates on the west. The Murray, perhaps the largest river in all Australia, arises amongst those mountains, and receives in its course various other rivers of considerable magnitude. These flow over extensive plains in directions nearly parallel to the main stream, and thus irrigate and fertilise a large extent of rich country. Falling from mountains of great height, the current of these rivers is perpetual, whereas in other parts of Australia the rivers are too often dried up and seldom indeed deserve any other name than chains of ponds.