d.
These are _Erebia aethiops_, _medusa_, _ligea_, and _ambla_.

Only one species of the well-known Polar genus _Oeneis_, viz. _Oe.
aello_ occurs in the Alps. It has always been taken at very high
elevations near the verge of the snow-line on the most lofty parts of
the Simplon Pass, and other similar situations. Altogether about a
dozen species of this genus of butterfly are known, most of which are
confined to the polar regions of the Old World and the New, though some
have found their way to the extreme south end of South America, in what
manner is still a mystery. Like the preceding genera, this also appears
to have emerged from Central Asia. The genus, too, is closely allied to
the last, and though its range is not quite so extensive, it resembles
it in many respects. The Alpine species of _Oeneis_ came to Europe by
the Oriental route. But the Lapland species--at any rate _Oe. jutta_
and _Oe. bore_--have taken a somewhat circuitous route to reach our
continent. They first migrated from Asia to North America, and then by
the old land-connections by way of Greenland to Lapland. It is
noteworthy that Professor Engler felt convinced (cf. p. 171) that the
occurrence of many of the Arctic plants in North Scandinavia and Siberia
could be best explained by the assumption of such a migration from Asia
_via_ North America to Europe rather than by the shorter route.

There are far more Alpine beetles than butterflies, but their
geographical distribution is less well known, and it is therefore not at
all safe to base important conclusions as to the origin of a fauna on
that group alone; however, as far as my limited knowledge of the
_Coleoptera_ of the Alps goes, their general range seems to agree
perfectly with other orders of insects. Many can also be traced to an
Asiatic home, and the route they came by is the Oriental and not what I
have called the Siberian.

Take, for instance, the genus _Nebria_, of which we have one species in
England--a black insect with a bright reddish-yellow border and long
light legs--known as _N. livida_. There are about eighty European
species, most of which are confined to the Alps, the Caucasus, the
Pyrenees, Spain, and Greece. The genus, however, ranges all over the
Holarctic Region, that is to say roughly, over Europe, Central and
Northern Asia, and North America. The centre of distribution lies in
Central Asia. If the genus had poured into Europe by the northern or
Siberian route, we shou