The History of the European Fauna

by R. F. Scharff

Zonites is, according to Dr. Kobelt, a third Alpine genus, whose range scarcely differs from the other two (b, i., p. 254). The centre of distribution lies at present in one of the branches of the most southern Alpine chain which help to form a large portion of the Balkan peninsula. The bulk of the species inhabit that peninsula, the Greek Islands (except Crete) and Asia Minor. Neither in the Tyrol nor in Switzerland do we find any Zonites, and the few species that do occur in the south-eastern Alps only just cross the outliers of these mountains. Between the south-western Alps and the Rhone we again find a Zonites—a remarkable case of discontinuous distribution, since the nearest other habitat of the genus is Monte Gargano in South-eastern Italy, which is known to harbour a good many interesting geographical puzzles.

We still have a good deal to learn as regards the molluscan fauna of Sicily, Sardinia, and Corsica. These islands have scarcely been more than skimmed by conchologists, and Zonites may inhabit one or all of these, which might indicate to us the manner in which this genus travelled from Southern Italy to Provence in the south of France. The distribution of Zonites certainly does not seem to imply an Alpine origin, because it is almost completely absent from the Alps proper. But I do not think my views differ materially from those of Dr. Kobelt, since the Alps, in the wide sense, include the mountains of the Balkan peninsula, where I should feel inclined to locate the ancestral home of the genus.

The small operculate genus Acme is a similar case. Dr. Kobelt places the centre of distribution on the southern slope of the Alps, but scarcely any of the species inhabit the Alps proper. Some occur in France, others in North Africa, Sicily, Southern Italy, and the Caucasus. It is evidently a very ancient genus. The species live in moss or underground, and are not likely to be transported across the sea by accidental or occasional means of distribution.

Still another genus, which resembles Acme in its geographical distribution, is Daudebardia—a small slug-like mollusc with a tiny shell. It does not, however, range nearly so far north or west as Acme, for it occurs neither in the British Islands nor in Spain or the Pyrenees.

I shall not be able to refer to more than a few of the most typical Alpine species of Lepidoptera, but they may be taken as fair examples of the geographical distribution of the rest of the group.

Even those visitors to Switzerland who do not claim to be naturalists have heard of the remarkably handsome and stately Butterfly known as Apollo. To the ardent entomologist, the first sight of this typical Alpine species is a never-to-be-forgotten delight, and he generally brings home with him a rich harvest of specimens. The more experienced Butterfly hunter knows that there are no less than three different kinds of Apollo—or, as we should say more correctly, of Parnassius—in Switzerland. There is first the common Apollo (Parnassius Apollo), then the rarer and more local P. delius, which inhabits more elevated regions, and finally the still scarcer P. mnemosyne, which is only known from the highest mountain ranges. It may be a surprise to those who have accustomed themselves to connect Apollo with the Alps, and who think the two belong together and cannot do without one another, to hear that it is by no means confined to them. It is also found in Scandinavia, France, Spain, Russia, and in Siberia. Parnassius delius is confined to the European Alps and the mountains of Central Asia, while P. mnemosyne is known from the Pyrenees, Sweden, Hungary, Sicily, Russia, and Western Asia. One other Parnassius inhabits Europe, viz., P. Nordmanni of the Caucasus, but all the remaining species of the genus—and there are nearly thirty more—are confined to Central Asia. A few, as we have seen, have reached Europe, some have travelled to the Himalayan Mountains, and others to Western North America. The centre of distribution is certainly in Central Asia, and we have no reason to suppose that the original home in this case does not agree with that centre.

Melitæa, a genus to which some of our British Fritillaries belong, 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 Altaï Mountains, which again are near the centre of distribution, since some species of Melitæa 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. æthiops 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 Altaï 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 period. These are Erebia æthiops, medusa, ligea, and ambla.