craft, and has two or three small tributaries from the west. Two
small streams empty into Lake Pampa Aullaguas, which has a small outlet
in the Lacahahuira flowing west for 60 m. to the Cienegas de
(salt-swamps of) Coipasa. The drainage of this extensive district seems
to be wholly absorbed by the dry soil of the desert and by evaporation.
In the extreme south the Rio Grande de Lipez is absorbed in the same
way.

Few of the Bolivian lakes are at all well known. The great lacustrine
basin between the Beni and the Mamore contains several lakes and
lagoons, two of them of large size. These are Lake Rogagua whose waters
find their way into the Beni through Rio Negro, and the Roguaguado
lagoon and marshes which cover a large area of territory near the
Mamore. The latter has an elevation little, if any, above the level of
the Mamore, which apparently drains this region, and its area has been
estimated at about 580 sq. m. Lake Conception, in the Chiquitos
mountains, belongs to this same hydrographic area. In the south-east
there are several large shallow lakes whose character and size change
with the season. They fill slight depressions and are caused by
defective drainage. Near the Paraguay there are several of these lakes,
partly caused by obstructed outlets, such as Bahia Negra, Caceres,
Mandiore, Gaiba and Uberaba, some of them of sufficient depth to be
navigable by small craft. Above the latter are the great Xarayes swamps,
sometimes described as a lake. This region, like that of the north, is
subject to periodical inundations in the summer months (November-March
or even May), when extensive areas of level country are flooded and
traffic is possible only by the use of boats. The two principal lakes of
the plateau region are Titicaca and Pampa Aullaguas or Poopo. The former
lies near the north end of the great Bolivian _alta-planicie_, 12,644
ft. above sea-level, being one of the most elevated lakes of the world.
It is indented with numerous bays and coves; its greatest length is 138
m., and its greatest breadth 69 m. According to a survey made by Dr M.
Neveau-Lemaire (_La Geographie_, ix. p. 409, Paris, 1904), its water
surface, excluding islands and peninsulas, is 1969 sq. m., and its
greatest depth is 892 ft. The level of the lake rises about 5 in. in
summer; the loss in winter is even greater. The lake belongs to both
Bolivia and Peru, and is navigated by steamers running between Bolivian
ports and the Peruvian railway