The river MARANON rises in the southern Andes of Peru, and if its length is estimated from its known parts only, to the Atlantic, it rolls its waters through a space equal to 4500 miles, and it is said that a vessel of 4 or 500 tons, might actually navigate it throughout this immense extent. It receives on every side along its majestic course, streams which are themselves longer and deeper than most of the great rivers of Europe; the _Beni_, the _Lauricocha_ or _Tunguragua_, the _Madera_ or _Llavari_, and the _Negro_, are all of this description; besides which, as a late traveller in Brazil has observed, it may be said to receive thousands of others into its bosom. Near its supposed sources, this noble stream, or rather inland sea, is called the APURIMAC, and rises to the south of the mountains of Cailloma, between 16 and 17 degrees of south latitude, near the city of Arequipa, where it is joined by the _Monigote_ or _Panguana_, and is so deep that on entering the province of Canes, a rope bridge becomes necessary. Eight miles below this bridge it passes through the Andes, amid awful precipices, and is joined by the _Pampas_ or _Charcas_ in 13° 10ʹ south latitude from the west. The _Vilcamayo_, nearly equal in size to the Apurimac, falls into it, at 12° 15ʹ south latitude, and the Rio _Jauja_, or _Mantaro_ in 12° 6ʹ south latitude. At the junction of this stream with the Apurimac, the current which had before run from north-west, changes to the north-east. The _Perene_ at 11° 13ʹ, and the _Ynambari_, or _Paucartambo_, at 10° 45ʹ, augment its swelling waters, after which, from hence to 8° 26ʹ south latitude, it receives forty large streams; but none so considerable as the BENI, whose sources lie in the province of Sicasica, in 19° south latitude. At its confluence with this river, the Apurimac is called the GRAND PARA, and is two miles in width; and at 8° 26ʹ south latitude; the _Pachitea_ throws in its tributary waters. Northward of this last the _Piachiz_ joins it, and here the river changes from north to north-east. At 7° 35ʹ south latitude, the _Aguaytra_ falls into it, and in 7° south latitude, the _Manoa_ or _Cuxniabatay_, the _Sariacu_ at 6° 45ʹ south latitude, and the _Tapichi_ at 5° south latitude. The stream has now borne for some time the name of UCAYALE, and proceeding under this appellation, with an immense volume, it receives at 4° 55ʹ south latitude, the _Tunguragua_, _Lauricocha_, or _False Maranon_. It now divides into three branches, the largest of which is 55 fathoms in depth, and turns directly to the east. Before describing its farther progress, it is necessary to say that some authors have doubted whether the Beni is not the true Maranon, as its sources are farther south than those of the Apurimac; and it is of such force, and has such an immense width on its junction with that river, that it actually drives the Apurimac towards the west for some distance.