After traversing the country between Paraguay and Brazil, the expedition proceeded north by the river Paraguay, and passed the mouths of the San Lorenzo, where it entered the great lake Gaiva, and from thence the greater lake Uberava, the limits of which could not be traced, being lost in the horizon. An Indian told the Count that he had travelled for three whole days in his canoe, without finding its extremity, which supposes a length of twenty-five or thirty leagues. This great inland sea is unknown to geographers. At Villa Maria a caravan of mules awaited the travellers, when they entered the desert or Gran Chaco, as it is called, and proceeded to the town of Matto-Grosso, which is considered the most pestiferous place in the world. Out of a population of 1200 souls, there were found but four whites, of whom three were officers of the government; all the rest was composed of blacks and Indians of every variety and color, who alone are able to support this terrible climate. From this place the expedition proceeded to Santa Cruz of the Sierra, where they found bread, of which they had been deprived for two years; after a month's repose, a journey of eight days brought the party to Chuquisaca, in Bolivia, and from thence by Potosi to Lima. The results of this expedition are already of great interest. It will make known people, the names of which were unknown to geographers. Rivers which appear on our maps are found not to exist, while hitherto unknown rivers and large bodies of water have been discovered. Many geographical positions have been determined, and the particulars of the trade which is extensively carried on in the centre of this vast continent by means of caravans of mules, are made known. M. de Castelnau has paid particular attention to the productions of the country, with a view of introducing such as are valuable into the French colony of Algeria. Large collections in Natural History have already been received at the museum in Paris; observations on terrestrial magnetism and meteorology have been made, in fact, no department of science seems to have been neglected by the expedition, which will reflect great credit on its distinguished head, Count Castelnau, as well as on the French government, by whose liberality and zeal for the promotion of science it has been supported. From Lima, Count Castelnau intended to prosecute further researches in the country of the Incas, after which he would proceed to the Amazon river.