The History of the European Fauna

by R. F. Scharff

The second district contains some species of molluscs which are almost entirely absent from the first, such as Geomalacus maculosus, Testacella Maugei, Helix pisana, Helix revelata, Helix acuta, and Pupa ringens. These are all of Lusitanian origin, and do not occur in Central Europe. Scotland alone cannot be classed as a separate province, since it does not contain a single species peculiar to itself. But, along with Ireland and the South-west of England and Wales, it is distinguished from the remainder of these countries by the almost total absence of what have been called Germanic types.

A French conchologist, the late Dr. Fischer, dealt with the British molluscan fauna in a somewhat similar spirit (p. 57). He divided the British area into two districts, but these differ from mine in so far as the South-west of England and Wales and the West of Ireland form one; the remainder of England and Ireland as well as the whole of Scotland the other. His classification is of particular interest, since the first district represents part of a larger Atlantic province, the second a portion of the Germanic province of the European sub-region. The latter he looks upon as one of the sub-regions of the great Palæarctic Region. Attention is thus drawn to the intimate relationship existing between the western parts of the British Islands and the Spanish peninsula on the one hand, and between the eastern portions and Central Europe on the other.

Mr. Jordan's North-Sea-and-Baltic district includes Scotland and the North of Ireland, whilst England joined with the West and South of Ireland forms part of his Celtic province. Both of these districts or provinces belong to Mr. Jordan's greater Germanic Region (p. 302).

In the collection illustrating the geographical distribution of animals in the Dublin Museum, the British species have been grouped into three divisions. One contains those with a wide range over the British Islands, another the characteristic forms of the south-east and lowland districts of Great Britain, and the third the Irish and the western and highland Anglo-Scotian species. Mr. Carpenter has named the last two divisions the "Teutonic" and the "Celtic." More recently, he has recognised that this last division contains two distinct groups; one including animals of northern, the other those of southern origin. He acknowledges indeed, just as I do, three distinct faunas in the British Islands, with the addition of the group of generally distributed species of undetermined origin.

Many other naturalists have worked in the direction I have indicated—namely, in grouping the British animals into several distinct assemblages, without, however, taking their foreign range into consideration, or their origin. I have already referred to the useful work done by botanists, who have been the pioneers in the science of the geographical distribution of living organisms. Among the British naturalists who have applied the principles of Watson to zoology, A. G. More deserves to be specially mentioned. He was the first to make a serious study of the British fauna on the lines laid down by that distinguished botanist. In conjunction with E. Boyd, he published a valuable essay on the "Distribution of Butterflies in Great Britain," and later on the birds were similarly dealt with. All the more important groups of animals are now being studied with a view to determining their exact range in these islands. Mr. Harvie-Brown, Mr. J. W. Taylor, Mr. Eagle Clarke, Mr. Miller Christy, Mr. Ussher, Mr. Barrington, and a number of others have considerably advanced our knowledge in this direction in recent years.

Any such contributions are to be welcomed as furnishing us with the necessary data to solve the problem of the origin of the British fauna. Meanwhile we know enough to enable us to assert positively that the latter has reached us by land-connections from various parts of Europe (cf. p. [35]). This statement of course refers to the bulk of the British fauna. The small proportion of indigenous species, or such as have been introduced accidentally, may be left out of consideration when dealing with the great mass of animals which have evidently migrated to the British Islands on land now sunk beneath the sea (see [Fig. 4], p. [60]). Opinions of zoologists, botanists, and geologists are practically unanimous on this subject; yet there are two other theories, which have from time to time been advanced to account for the origin of the British fauna. Only the first of these, however, can claim the serious attention of those interested in the problem. Its chief contention lies in the oft-asserted dictum of the "imperfection of geological record." It has been suggested, in fact, that the British fauna, instead of having migrated to our islands, might have originated there, but that, owing to the fragmentary nature of our Tertiary deposits, all trace of their early history had disappeared. "The origin of European species," remarks Professor Cole (p. 238), "within the area of the British Isles, and their migration outwards when local conditions became less favourable for their multiplication, are possibilities that seem too often disregarded. Yet the geologist must see in the western borderland of modern Europe a diminished continent from which land-animals must have again and again moved eastward." "Hence geologists may fairly be unwilling to look on our isles as barren lands waiting to be peopled in pliocene or later times. Far rather has the breaking up of a broad land-area along the present continental edge sent our land-fauna to the new steppes that opened eastward, leaving us a mere diminished remnant to struggle with the glacial period."

There are in Professor Cole's views many points with which I readily agree. In the first place, he acknowledges that migration has taken place on land, so that we have our land-connection between Great Britain and the Continent whatever theory we accept as to the direction taken by the migrants. That the western borderland of Europe has given rise to many important assemblages of animals in past times, seems to me also exceedingly probable, nor do I look upon the British Islands as "barren lands waiting to be peopled in pliocene or later times." On the contrary, I believe an almost uninterrupted stream of migrants poured into the British Isles before pliocene times from the south. But what I thoroughly disagree with, is the remark that our British land-fauna has been sent to the new steppes that opened eastward. These are the more or less arid portions of Eastern Europe. Professor Cole no doubt has in mind those species of mammals which I have included in what I called the Siberian migration, and of which we have fossil evidence in the late Tertiary deposits of Europe. It would be impossible here to discuss this subject fully, especially as I have done so in the subsequent chapters; but, even if we had no geological record whatsoever, the present range of the species in question and their nearest relatives must convince us that they could not have originated in Western Europe. However, on the strength of the geological evidence, Professor Nehring—the only one who has made this fauna his special study—remarks (p. 228), that there seems scarcely any doubt that this steppe-fauna just referred to had come to us from the east. Professors Boyd Dawkins, Brandt, and Lartet held similar views.

The theory that an ice-sheet stretched across a narrow sea might be the means of aiding a fauna across from the mainland to an island, is particularly inapplicable to the British Islands. Neither Mr. Kinahan nor Mr. Lamplugh, the two supporters of this view, have, however, taken the trouble to apply it to more than one species of the British fauna. An ice-bridge, thinks Mr. Kinahan, "could easily have connected Scotland and Ireland, thus giving a land causeway for migration" (p. 3). Mr. Lamplugh throws more light on this interesting speculation by giving us the name of an animal which he believes crossed a narrow sea on a bridge of ice. This animal unfortunately happens to be one whose remains have never been found in high northern latitudes, viz., the Irish elk (Cervus giganteus). And because he is of opinion that this species of extinct deer found its way to the Isle of Man from the mainland on a waning ice-sheet, he sees no reason why certain elements of the Irish fauna should not have been similarly introduced.

It seems of no advantage to begin the discussion on the origin of the British fauna by assuming the former existence of ice-bridges, and the possibility of a migration across them of some of its members. If a glacier connected Scotland and Ireland, the climate of both countries (since they were highlands and acted as the feeders of the ice-sheet) must have been uncomfortable to the majority of the British species. What were the inducements that could have prompted those which had braved the discomforts of Scotland to emigrate to Ireland at such a time? What light does it throw on the origin of the Irish fauna as a whole, to advance the extremely improbable hypothesis that certain elements of it may have reached Ireland by an ice-bridge? If any species came to that country in such an unusual manner, surely they must have been Arctic or northern forms. But what about the southern species, which form the bulk of the Irish fauna and also the flora? Even the Arctic element of the British fauna, which probably includes, besides the Reindeer, many hundreds of species, could not, I think, have migrated to these islands on an ice-bridge. Indeed, I agree with most of the writers who have dealt with the subject, in asserting that the northern as well as all the other elements of our fauna utilised for their migration the old land-bridges which connected these islands with one another and with the Continent.

There is a greater diversity of opinion as to the age during which the British fauna arrived in these islands. This is naturally a much more complicated problem, but it is one which I am convinced will ultimately be solved mainly by means of a study of the geographical distribution of animals and plants. If we can settle the relative ages of the various migrations, we thereby supply an important link in our attempt to reconstruct the past geographical features of the British Islands. The range of the British species will give us an idea of the nature of the land-connections and their gradual changes in course of time. Geological data are exceedingly valuable in these inquiries, but it is a fatal mistake to build our geographical theories and the origin of the British fauna as a whole entirely on the assumptions of a certain school of geologists. Unfortunately, Dr. White's very interesting remarks on the British fauna for this reason lose much of the value which they might otherwise possess.