Desert, and perhaps some other watercourses of a similar character coming from the westward. This peculiar structure of the interior renders it improbable that any considerable inland lakes should exist in connection with the known system of waters; for, as Lake Torrens is decidedly only an expanded continuation of Cooper's Creek, and therefore the culminating point of this vast system of drainage, if there was sufficient average fall of rain in the interior to balance the effects of evaporation from the surface of an extensive sheet of water, the Torrens Basin, instead of being occupied by salt marshes, in which the existence of anything beyond shallow lagoons of salt-water is yet problematical, would be maintained as a permanent lake. Therefore, if the waters flowing from so large a tract of country are insufficient to meet the evaporation from the surface of Lake Torrens, there is even less probability of the waters of the western interior forming an inland lake of any magnitude, even should there be so anomalous a feature as a depression of the surface in which it could be collected, especially as our knowledge of its limits indicate a much drier climate and less favourable conformation of surface than in the eastern division of the continent. The undulations of the surface of the country are nearly parallel to the meridian, gradually decreasing in height from the dividing range between the eastern and western waters till, instead of the waters of the rivers being confined to valleys, they occupy plains formed by a slight flattening of the curvature of the sphere. Thus the sides of the plain through which the river ran before it turned west to Cooper's Creek were 150 feet below the tangential level of the centre channels, and even the summit of the sandstone tableland which rose beyond was below the visible horizon. It is this peculiar conformation which causes the stream-beds to spread so widely when following the course of the valleys from north to south, and it is only where they break through the intervening ridges that the water is confined sufficiently to form well-defined channels. The existence of these extensive valleys trending north and south over so large a tract of country render it by no means unlikely that they continue far beyond the limits of present explorations, and it is not unreasonable to infer that the great depression which has been traced nearly five hundred miles north from Spencer's Gulf through Lake Torrens to the stony desert of Sturt (or rather the mud plains contiguous to its western limit) may be continuous for an equal distance beyond to the low land at the head of the Gulf of Carpentaria; a theory also supported by the fact that the rivers flowing into the Gulf either come from the east or west, apparently from higher land in those directions, while there is not a single watercourse from the south, or any indication of elevated country in that direction. Captain Wickham having named an important river