erected on the ice in the middle of the lake, and it
remains frozen till the second half of May. The evaporation from this large
basin exercises a certain influence on the climate of the surrounding
country, while the absorption of heat for the thawing of the ice has a
notable cooling effect in early summer.

_Rivers_.--Lake Baikal receives over 300 streams, mostly short mountain
torrents, besides the Upper Angara, which enters its north-east extremity,
the Barguzin, on the east, and the Selenga on the south-east. Its only
outflow is the lower Angara, which issues through a rocky cleft on the west
shore. The Irkut no longer reaches the Baikal, though it once did so. After
approaching its south-west extremity it abandons the broad valley which
leads to the lake, and makes its way northwards through a narrow gap in the
mountains and joins the Angara at Irkutsk.

_Mountains_.--With the exception of the delta of the Selenga, Lake Baikal
is surrounded by lofty mountains. The Khamar-daban border-ridge (the summit
of a mountain of the same name is 5300 ft. above the lake), falling with
steep cliffs towards the lake, fringes it on the south; a massive,
deeply-ravined highland occupies the space between the Irkut and the
Angara; the Onot and Baikal ridges (also Primorskiy) run along its
north-west shore, striking it diagonally; an Alpine complex of yet
unexplored mountains rises on its north-east shore; the Barguzin range
impinges upon it obliquely in the east; and the Ulanburgasu mountains
intrude into the delta of the Selenga.

_Geology_.--It is certain that in previous geological ages Lake Baikal had
a much greater extension. It stretched westwards into the valley of the
Irkut, and up the lower valleys of the Upper Angara and the Barguzin.
Volcanic activity took place around its shores at the end of the Tertiary
or during the Quaternary Age, and great streams of lava cover the Sayan and
Khamar-daban mountains, as well as the valley of Irkut. Earthquakes are
still frequent along its shores.

_Fauna_.--The fauna, explored by Dybowski and Godlewski, and in 1900-2 by
Korotnev, is much richer than it was supposed to be, and has quite an
original character; but hypotheses as to a direct communication having
existed between Lake Baikal and the Arctic Ocean during the Post-Tertiary
or Tertiary ages are not proved. Still, Lake Baikal has a seal (_Phoca
vitulina_, _Phoca baikalensis_ of Dybowski) quite akin to the seals of
Spitsber