has
also some typically Alpine members. Two of these, viz. _M. cynthia_ and
_M. asteria_, are peculiar to the Alps, the latter being only found at
considerable elevations. Most of the remaining fourteen European species
are also found in Central Asia. Thus the isolated _M. maturna_, which in
Europe is confined to Lapland, is also known from the Altai Mountains,
which again are near the centre of distribution, since some species of
_Melitaea_ range across the Northern Pacific to Western North America.

The small British Mountain Ringlet, and also the Scotch Argus, belong to
a genus of butterflies which is very characteristic of the European
Alps. But owing to its enormous geographical distribution, its probable
home is somewhat difficult to ascertain. Nevertheless it is a noteworthy
genus, especially so from the fact that the two British species _Erebia
epiphron_ and _E. aethiops_ are taken at first sight for true Arctic
migrants. As neither of them, however, occurs in Scandinavia, Greenland,
or Arctic America, this supposition must be abandoned. They must be
looked upon as species which once had a wider range in the southern
parts of the British Islands, and which have survived in a few isolated
localities, where they are apparently on the verge of extinction.

About sixty species of _Erebia_ are known to science, half of which are
found in Europe, the remainder in Siberia, the Himalayas, Arctic
America, Chili, Patagonia, South Africa, and Madagascar. Though a few do
range into these outlying regions of the earth, Central Asia seems to
lie near the centre of distribution of the genus, and the probability is
that it also was its original home. Most of the European species are
high Alpine forms--_E. glacialis_ being met with at a height of 10,000
feet--and these are generally quite peculiar to the Alps, showing that
their ancestors came from Asia at an early date, probably by way of Asia
Minor and Greece. A few, as for instance _E. lappona_, range right
across to the Altai Mountains from the Alps, and at least one--_E.
melas_--is found in Greece. _Erebia_ migrations seem therefore to have
taken place by the Southern or Oriental route at different geological
periods. But some of the European species which are more or less
confined to the plain, and are either absent from Switzerland or do not
reach the higher elevations, appear to me to have come by the more
direct northern or Siberian highway, at a still more recent perio