The History of the European Fauna

by R. F. Scharff

In his remarkable essay the late Edward Forbes affirms that the flora peculiar to the west of Ireland, of which the strawberry tree (Arbutus unedo) is the most striking example, and which exhibits such strong southern affinities, is not only much the most ancient of our island floras, but that it is actually of miocene age. It migrated to Ireland from Spain at a very remote period, during which he supposed that a direct land-connection existed between the two countries. The destruction of this old land-bridge, he thinks, must have taken place before the commencement of the Glacial period. Climatal changes during that time destroyed the mass of the southern flora which had thus reached Ireland, the survivors being species such as were most hardy (saxifrages, heaths, etc.), which he considers to be the only relics of this most ancient portion of our flora.

The northern or Arctic fauna and flora, according to the same author, established themselves in the British Isles during the Glacial period—at a time when these were groups of islands in the midst of an ice-bound sea. Finally, the great mass of our animals and plants migrated from the Continent to England after the Glacial period. "The migration of the species," he says, "less speedy of diffusion, which are now peculiar to England was arrested by the breaking up of the land-connection between England and Ireland, and thence the famous deficiencies of the sister isle, as, for instance, its freedom from reptiles" (p. 10). He is also of opinion, that the separation between England and the Continent took place at a later date than that between England and Ireland.

According to Dr. A. R. Wallace (p. 338), we possessed just before and during the Glacial period "a fauna almost or quite identical with that of adjacent parts of the Continent, and equally rich in species." But the submersion, he thinks, which is supposed to have occurred during the latter part of the Glacial period, destroyed the greater part of the life of our country. When England again became continental, continues Dr. Wallace, this fauna was succeeded by an assemblage of animals from Central Europe. "But sufficient time does not seem to have elapsed for the migration to have been completed before subsidence again occurred, cutting off the further influx of purely terrestrial animals, and leaving us without the number of species which our favourable climate and varied surface entitle us to." The comparative zoological poverty of Ireland he attributes to the fact that "the depth of the Irish Sea being somewhat greater than that of the German Ocean, the connecting land would there probably be of small extent and of less duration, thus offering an additional barrier to migration."

Dr. Wallace's explanation of the origin of the British fauna is disappointing after Forbes's careful study and critical inquiry into its component elements. So great an authority on geographical distribution might have given us more lucid statements of his views on a variety of topics connected with this subject.

In speaking of the fauna of Ireland, Professor Leith Adams, Professor Dawkins, and Mr. Alston are evidently only thinking of the mammals, which form but a very small proportion of it. The first-mentioned palæontologist held that there was a land-communication between Scotland and Ireland at the close of the Glacial period, by which the greater portion of the mammals that had found their way to the former country crossed to the latter (p. 100). And, he continues, the severance between the two countries must have taken place before the slow-travelling Mole, the Beaver, the forest-haunting Elk and the Roebuck had time to arrive.

Much in the same spirit are Mr. Alston's remarks on this subject (p. 5). "The absence from the known fossil fauna of Scotland and Ireland of most of the characteristic post-pliocene English animals, shows that the northward migration of these forms was slow, gradually advancing as the glacial conditions of the northern parts of our islands decreased in intensity. Thus it is not difficult to suppose that the Hedgehog, Ermine, Badger, Squirrel, and Mountain Hare may have found their way through southern Scotland into Ireland long before they were able to penetrate into the still sub-arctic regions of the Highlands. Subsequently, when the improvement of the climate had continued, the Shrews and Voles may well have found their way northward along the comparatively genial coasts, before the larger beasts of prey could find a sufficient stock of game."

That the Bear, Wolf, Stag, Horse, Mammoth, and Reindeer lived in Ireland before the Glacial period is considered highly probable by Professor Boyd Dawkins (a, p. 152).

Only the Butterflies are dealt with in Dr. Buchanan White's clever little essay on distribution. And, as I remarked before, his conclusions are somewhat marred by the unwarrantable assumption that our islands at no distant date were totally destitute of all plant-life, and were therefore uninhabitable by animals. But his paper differs in so far from most of the others, that he has made a thorough study of the one group he deals with. In some respects it may serve as a model to future students in its general treatment of the problem he has set himself to work out. He adopts the principle, even for butterflies, that though it is possible for them to be blown over from the Continent, they have probably migrated with the rest of our indigenous fauna and flora across the dry bed of the German Ocean. His conclusions are that Britain derived its butterfly fauna from continental Europe in post-glacial times, that the Arctic and Alpine species were the first arrivals, and that one part of the Irish species reached Ireland by way of Scotland, another from the south. He assumes, of course, that Great Britain and Ireland were connected at that time.

Within the last few years the spell which has bound naturalists to accept the theory of a total destruction of life during the Glacial period is happily vanishing, and more enlightened views are gaining ground. The Lusitanian species of plants in the west of Ireland, which had already furnished Forbes with an argument in favour of survival, are also regarded by Mr. Bulman as the remnants of a pre-glacial flora which was exterminated everywhere else by the cold (p. 265). This view of the survival of a pre-glacial fauna and flora has since been accepted by Mr. Carpenter, whilst I also have endeavoured to bring fresh evidence into the field in its favour. We both agree with Edward Forbes in considering the Lusitanian element as the oldest section of our fauna and flora, and that it came long before the Glacial period. But we differ somewhat from him, in so far as we do not limit that element to Ireland. It seems also to be represented in South-western England and Wales, though it is there less conspicuous.

This decision as to the relative age of the British South-western fauna has not been arrived at from any geological considerations. The conviction that it must be older than the other sections has been gained solely from a study of the geographical distribution of the species belonging to that fauna. Many of them exhibit what is known as "discontinuous distribution," which zoologists are agreed to regard as a sign of antiquity. Thus Geomalacus maculosus, the Kerry Slug, is in the British Islands confined to South-western Ireland (see [Fig. 19], p. [300]), and on the Continent it is unknown north of North-western Spain. The Millipede, Polydesmus gallicus, has a wider range in Ireland, and is also known from France and the Azores. Two Earthworms of the Spanish and Mediterranean region, viz., Allolobophora veneta and Georgii, have been discovered in Ireland, but are apparently unknown in England or France; whilst the Weevil, Otiorrhynchus auropunctatus, does not occur north of the Auvergne Mountains in France except in Ireland. A very large number of instances might be mentioned of species found in South-western Europe, France, the South-west of England and Ireland. Enough, however, has been said to show the nature of the fauna, and there is, as Forbes has pointed out, a corresponding flora.