per course.

South of Cape Frio there are no large rivers along the coast because
of the proximity of the Serra do Mar--the coastal plain being very
narrow and in places disappearing altogether. There are many short
streams along this coast, fed by heavy rainfalls, but they have no
geographic importance and no economic value under existing conditions.
The largest of these and the only one of commercial value is the
Ribeira de Iguape, which has its source on the tablelands of Parana
and after receiving several affluents west of the Serra do Mar breaks
through a depression in that range and discharges into the Atlantic
some miles below Santos on the southern boundary of the state of Sao
Paulo. This river has a navigable channel of 118 m. below Xiririca,
and communicates with an inland canal or waterway extending for many
miles along this coast and known as the Iguape, or Mar Pequeno. In Rio
Grande do Sul the Atlantic coastal plain extends westward more than
half-way across the state, and is well watered by numerous streams
flowing eastward to the Lagoa dos Patos. Of these only two are of
large size--the Guayba and Camaquam. The first is formed by the
confluence of the Jacuhy, Cahy, Sinos and Gravatahy, and is known
under this name only from Porto Alegre to the Ponta de Itapua, where
it enters the Lagoa dos Patos. This river system drains a large part
of the northern mountainous region of the state, and has a
considerable extension of navigable channels between the plateau
margin and the lake. In the extreme southern part of the state, the
Lagoa Mirim empties into the Lagoa dos Patos through a navigable
channel 61-1/2 m. long, called the Rio Sao Goncalo.

The Brazilian rivers of the Rio de la Plata system are numerous and
important. Those of the Paraguay drain the south-western part of Matto
Grosso, and the tributaries of the Parana cover the western slopes of
the Serra do Mar from Rio Grande do Sul north to the south-west part
of Minas Geraes, and include the south-east part of Matto Grosso and
the south part of Goyaz within their drainage basin. This is one of
the most important fluvial systems of Brazil, but its economic value
is impaired by the great waterfalls of Guayra, or Sete Quedas, and
Uribu-punga, and by the rapids and waterfalls in the majority of its
affluents near their junction with the main stream. Between the two
great waterfalls of t