Here and there, in the progress of my work, I have casually referred to the Rio de la Plata and its affluents; but the fluvial system which they together constitute is certainly deserving of more than a merely cursory comment. I will, therefore, add to my remarks on the Amazon and its tributaries some more precise observations with respect to the numerous rivers which give access to the fertile regions of Paraguay and furnish the Argentine Confederation with an extensive littoral coast.

The rivers Parana, Uruguay, and Paraguay are, however, now too well known to necessitate any very minute description. The first originates at no great distance from the shores of the Atlantic in that part of the table land of Brazil which divides the watershed of the Amazon from the watershed of the River Plate. Its most distant branch is the Rio Grande, which it receives at the confluence of the latter with the Paranahyba; and after an interrupted course of about 1,000 miles it finally effects a junction with the Paraguay, its largest affluent. Thence its huge volume of water, further augmented by the Uruguay, rolls to the ocean, forming that wide fresh water sea known as the estuary of the Plate. The Parana runs for nearly 900 miles within the limits of the Argentine Republic, and of this distance quite 750 are navigable throughout the whole year for sailing vessels and steamers of 300 tons burden. It begins to rise owing to intertropical rains towards the end of December, and this continues up to the close of April. Below its confluence with the Paraguay the average rise is eleven to twelve feet. The only tributary the Parana receives between its confluence with the Paraguay and its absorption in the estuary of the La Plata is the Rio Salado, a river of great length, and having its source in the Andine regions of the Argentine Confederation.

The Paraguay, like the Parana, has its origin in Brazilian territory. After passing through the Estrecho of Sao Francisco, (lat. 20° S.) it flows southwards, dividing the Republic of Paraguay from the Gran Chaco; a few miles below Asuncion, at a point called Angostura, the channel is narrowed by rocks, and the current becomes very rapid in consequence, taking a bend west by south until it mingles with the Parana. The Paraguay is navigable by large craft, and steamers have for some years ascended to Asuncion and Matto Grosso. The Paraguay receives the Pilcomayo, a very large stream of over 1,000 miles, and which, taking its rise near the city of Chuquisaca, in Bolivia, traverses a vast portion of that Republic, finally issuing from the Chaco wilderness at a point a little above Asuncion. Of course the Paraguay is augmented by numerous tributaries previous to its junction with the Pilcomayo, but these need not be specially mentioned. The Araguarmini empties itself into it at Oliva, and further down is the mouth of the Vermejo, a very considerable river, the navigation of which opens to commerce a territory of almost unrivalled fertility, and affords an easy access to Bolivia, in which State, like the Pilcomayo, it has its sources. Efforts have been made to facilitate the navigation of this fluvial highway, in connection with which the name of Sor. Arce is deserving of special allusion. This gentleman was the first to traverse the entire length of this previously unexplored river, his first descent having been effected in 1856. He followed its windings on a raft for a distance of 1,200 miles, penetrating in his course dense forests, and braving exposure to the rays of a tropical sun, not to speak of the danger incurred from wild beasts, and the yet more formidable Indian savages. The Vermejo will yet prove of incalculable advantage in conveying to the ocean the valuable products of the Argentine and Bolivian interior.

The Uruguay and the Parana partially enclose the Provinces of Entre Rios and Corrientes, and the former is only navigable from the sea as far as Salto, where rapids and falls occur; but above this point its waters are adapted to small steamers and sailing craft. Its source is in Brazil. On its banks are situated the towns of San Borja, Salto, Pysandu, Concepcion, Fray Bentos, and Soriano. It passes through a well wooded and picturesque country. Up to Salto it is constantly navigated by steamers trading between that place and the lower communities, especially Buenos Ayres and Monte Video.