The Araguaya, almost as extensive as the province, forms its western boundary from its embouchure to the origin of its principal head, which is in the vicinity of that of the Hipiaughuhi, there flows under the name of the Bonito, which, after gathering by the western bank the river Barreiros and by the eastern the Caiapo, takes the name of Rio Grande, by which it is designated when it traverses the road of Cuiaba. The first considerable river that unites itself with it after passing this road is the Rio Claro, which comes from the south-east, and brings with it the Fartura, that originates in the proximity of the Uruhu. One hundred miles to the north it receives by the same margin the Vermelho, which is inconsiderable when it passes the capital; a few leagues lower it gathers the Tizoiras, of little less volume and extent than the preceding; and nearly thirty miles further it is united by the Crixa, which is something larger than the others. All three flow from the south-east, and none of them with less than two hundred miles of course. Navigation has been conducted, by the central one, up to this day, from the capital to the city of Para. Thirty miles north of the mouth of the Crixa, which is also navigable, and has some salt pits in its vicinity, the Araguaya divides itself in the latitude of 12° 30′ into two branches nearly equal, which re-unite themselves in the parallel of 9° 36′, having formed the island of St. Anna, otherwise Bannanal, of one hundred and eighty miles in length, and of good width: there is a vast lake in the island which has an outlet into an arm of this river. The western arm preserves the name of Araguaya, and the eastern takes that of Furo, by which latter navigators commonly proceed. Both have falls, and a great number of islands, generally small, flat, and for the most part inundated during the periodical rains. The margins of the Furo are lower than those of the other arm, which latter receives by the western side various rivers, with which it is greatly augmented. The principal is the Mortes, which flows from the centre of Bororonia with near three hundred miles of course, and empties itself about forty miles north of the southern point of the island of St. Anna. At the northern extremity of this island the margins of the Araguaya are elevated a little to the confluence of that river with the Tucantines. The first navigators placed this confluence in 6°, the geographers of Para in 5°, and others in 3° 30′; the medium is evidently nearest the truth.