About two miles from hence is the principal of two mouths by which the Macacu enters the bay. It is one of its largest streams, and is navigable for fifteen leagues. Alligators of a very large size inhabit its banks, and take shelter amongst the high reeds which grow in the water. Its source is in the Organ Mountains, near the rock called Canudos, and it is united on its right margin by the rivers Guapiassu, Cabucu, and Varge; on its left by the Cacerebu and the Aldeia. The Guapiassu, which is the most considerable, comes from the same mountains as the Macacu; and, a little before its incorporation with that river, communicates with it by a channel called Rio dos Morros (River of Rocks.) There is a quarry of _pedra sabāo_, a peculiar stone, near its heads, which is excavated in large pieces, and sawn for the purpose of forming the mouths of furnaces in _engenhos_, or sugar-works, being considered of eternal duration. The principal confluent of this tributary river is Piracinunga, the main branch of which originates between the high points of the Organ Mountains. Betwixt the rivers Macacu and Guapiassu there is a certain portion of territory, comprising about two leagues, the most fertile in the district, which was bequeathed, in 1718, by André da Costa, as a legacy to some poor persons, with inalienable succession, and an annual pension of two missas, (masses,) for each house. This colony has now arrived at the number of twelve hundred individuals, and this bequest would maintain ten times as many, with adequate industry. The Guaxindiba flows from the Serra Taypu, and, describing numerous windings and turnings, enters the bay about two miles from the Macacu. The Emboassu, disemboguing four miles further, has its source in the Serra St. Gonçalo, and is navigable with the tide for a short distance.