The History of the European Fauna

by R. F. Scharff

Among the European Orthoptera—the group to which our Earwigs and Grasshoppers belong—there are also a good many instances of Oriental migrants. One of the most striking of these is the curious "praying insect" (Mantis religiosa). It occurs all over Southern Europe, and ranges as far north as the north of France. It is also found in Southern Germany and in Austria, and has a vast extra-European range. There are even records of its occurrence from all parts of Southern Asia and Java and a great part of Africa. That it belongs to an extremely ancient genus is testified by the fact of its presence in Mauritius, Japan, Australia, New Zealand, South America, and Madagascar. The genus Bacillus—to which the typical Stick-insects belong—has a somewhat similar geographical distribution. But no less than four species of Bacillus are known from Europe, according to our great authority Mr. Brunner von Wattenwyl—all from the south; and some of these also range into North Africa. There are thirty-two other species distributed over Southern Asia, Africa, Australia, New Zealand, and the Sandwich Islands.

Volumes, indeed, might be filled with lists of species and genera of terrestrial invertebrates of Oriental origin, but I will not weary the reader with further enumeration of such instances. Just two more, however, before concluding, as I have not alluded to the large group of the Arachnida.

Two peculiar spider-like genera, viz., Galeodes and Rhax, are found in Southern Europe. Both occur also in North Africa, and in Western and a portion of Southern Asia. As the whole family altogether has an Asiatic character, I cannot agree with Mr. Pocock, who considers them of European origin and believes that they are migrating eastward.

But not only terrestrial forms migrated to Europe from Western and Southern Asia. Freshwater species also took part in this great Oriental migration. I need only refer to the freshwater Crab (Thelphusa fluviatilis), with which Southern Europeans are familiar. It is the sole representative of a large genus which ranges east as far as Australia and southward to Madagascar and the Cape of Good Hope. The European species is found in Turkey, Cyprus, Greece, Southern Italy, Sicily, North Africa, Southern Spain, Syria, and Persia.

There is a corresponding flora with a range exactly similar to that of some of the animals quoted. Thus the Balkan Rhododendron (Rhododendron ponticum) is again met with in the western Mediterranean region in Southern Spain. The Cedar occurs in local varieties in the Himalayan Mountains, in the Lebanon, and the Atlas Mountains. Both of these are instances of discontinuous distribution, a proof of their antiquity; but a large number of plants have a continuous range between Asia Minor and Spain.

On looking through these few instances of what have been called Oriental migrants, one cannot help being struck by the fact that the species after their entry into Europe evidently did not all follow the same path during their westward advance. We have seen that a good many seem to have travelled either due west or north-west on entering our continent from Asia Minor. They may now perhaps be found in Greece, Southern Italy, Algiers, and Spain, also probably on some of the intervening islands in the Greek Archipelago, in Sicily, Sardinia, and Corsica, or they may have travelled north-east and occur in the Alps. This distribution indicates undoubtedly, as I have already set forth in another memoir (c, p. 459), that land extended from Asia Minor across Greece to Southern Italy, that the latter again was disconnected with Central Italy, but united with Sicily, Sardinia, and Tunis, and that the Straits of Gibraltar did not exist at the time when these species migrated westward. Some species are only to be found as far west as Southern Italy, while others occur in Central and Northern Europe, scarcely in the South, and not at all in the larger Mediterranean islands or in North Africa. This appears to me to indicate that the late comers from the east found that geographical changes had taken place in Southern Europe which prevented them from following the same track as the older immigrants. They were now obliged to turn directly northward and then westward. It may be asked, why should not the earlier migrants have taken the same route? This question will be answered immediately. Meanwhile it should be clearly understood that there probably was an older and a newer migration from the east. The Oriental genera—from whose general range we know that they must be very ancient indeed, such as Mantis and Bacillus—are almost invariably confined to Southern Europe. There they are frequently found on some of the Mediterranean islands. The earlier migrants therefore went westward and the later ones northward.

Let us now inquire a little into the reasons why such different courses were pursued by the migrants—why the Oriental migration divided into two streams, an older and a newer.

During early Tertiary times, and probably throughout the Miocene and Pliocene Epochs, the Ægean Sea did not exist. From the island of Crete to the Peloponnesus, and from Asia Minor to Thessaly and Macedonia, stretched a vast and fertile plain dotted over with numerous freshwater lakes. Gradually the sea encroached upon this land from the south, owing chiefly to extensive subsidences having taken place. Only very recently, says Professor Suess, did the whole of the Ægean continent subside (i., p. 437). Huge cliffs of levantine freshwater deposits now mark the new coast-line, and the Mediterranean advances steadily towards the Black Sea and the Sea of Asov. A new order of things is now established, continues the famous author of Das Antlitz der Erde; where there were high mountains we now behold a deep sea, in some places many thousand feet deep. All this took place quite recently,—geologically speaking,—certainly in post-glacial times; and man may even have witnessed these imposing events. Most geologists admit the correctness of these views. They are, moreover, built upon such solid geological evidence, that even if the science of zoogeography had not yet taught us anything, naturalists would not hesitate in accepting them.

Animals and plants were free to migrate from Central and Southern Asia to Greece by land for untold ages. The vast accumulation of mammalian bones which have been discovered at Pikermi, and so ably described by Gaudry, are probably to a large extent the remains of Asiatic immigrants to Europe. Many of these resemble forms still living in South Africa, which implies that a highway existed also at that time between Asia and Africa. Among these is a giraffe and antelopes closely allied to African species, and other most interesting mammals.