Under the Roman Emperor Augustus, the Spanish peninsula was divided into three provinces, one of which—namely Lusitania—occupied a large portion of the present area of Portugal. The term "Lusitanian" is therefore almost synonymous with Portuguese, but it has frequently been applied by zoologists and botanists in a much wider sense, so as to vaguely include the extreme south-west of Europe without any definite limits. Neither do I propose to restrict the term to everything found within the borders of Portugal. For the sake of convenience, we may designate as Lusitanian forms those animals and plants which have migrated to Central, Southern, or Northern Europe from South-western Europe. They may really be North-west African species, or they may have originated on land which lay to the west of Portugal, and which is now mostly buried beneath a deep sea. Nevertheless, we have received them from the extreme south-western portion of our continent—they have come to greater Europe from that direction.

In discussing the component elements of the British fauna and flora in the third chapter, I have already referred to the distinguishing characters of the Lusitanian migrants and to their distribution. I need only repeat, therefore, that these are now principally confined to the south-western portions of the British Islands. The late Edward Forbes was the first to trace the Lusitanian flora to its native home. In his classical memoir on the geological relations of the existing fauna and flora of the British Isles, he laid the foundations of a new method of research. We are as yet only beginning to realise the far-reaching conclusions obtainable by a careful study of the geographical distribution of animals and plants, though the lines of investigation were indicated by him more than fifty years ago. Forbes was of opinion that the Lusitanian element in the British flora was of miocene age, and that it survived the Glacial period on a now sunken land to the south-west of Ireland. Mr. Carpenter and myself agree in so far that we are both inclined to look upon this Lusitanian flora and the accompanying fauna in Ireland as of pre-glacial origin. But I am not quite satisfied that the Lusitanian migration ceased to come north then. It may have received a temporary check; but the presence, for instance, of the Dartford Warbler (Melizophilus undatus) in the south-east of England would seem to indicate that its northward migration took place in very recent times. It is possible also that the very restricted occurrence of the Dartford Warbler may imply that it is gradually withdrawing towards its centre of origin from a former wider range. Such an eventuality, as we have seen, has actually taken place in a great number of instances.

It is not only in the British Islands that we perceive the influence of the Lusitanian element. Scandinavia, Russia—indeed almost every part of Europe—can boast of some migrants which have originated in South-western Europe or on the mysterious lands which lay beyond it. As a rule, however, we notice a marked decrease of Lusitanian species as we travel eastward from Western Europe. Nevertheless, certain forms have travelled far beyond the confines of our continent, and we certainly meet with them in Asia and Northern Africa.

It is remarkable that we are apt to mistake sometimes for Lusitanian migrants species which are of Oriental origin. In a previous paper I classed such animals which had apparently originated in South-western Europe, but had really come from Asia by a circuitous southern route, with the Lusitanians. However, there is really no reason why the two should not be kept apart, provided we can discriminate between the pseudo-Lusitanians and the true ones. I have already indicated in the last chapter how these pseudo-Lusitanian migrants originated.

Supposing an Oriental species had left Asia for Europe in miocene times, it would on its arrival in Greece have had to decide between two courses. It could either advance into the newly-formed Alpine peninsula and there remain, or at once push on westward into Southern Italy, Sicily, and Tunis, by means of the old land-connections, and thence into Southern Spain. The Atlantic communicated at that time with the Mediterranean across the valley of the Guadalquivir; but that connection ceased to exist towards the end of the Miocene Epoch, when the Oriental migrants were free to ramble through Spain and the whole of the North European plain. I have indicated on a previous occasion (a, p. 484) that the earliest members of the Red Deer migration, which have left their traces in the caves of Malta, and whose descendants still live in Corsica, Sardinia, and North Africa, may have found their way to Northern Europe in this manner. Many other Asiatic mammals probably reached the British Islands in a similar way.

I cannot call to mind any large species of mammal which we might reasonably suppose to have originated in South-western Europe. Even among the smaller ones, few give us any definite clue in this respect. For instance, the present range of the genus Myogale—a small Insectivore belonging to the Mole family (TalpidÆ)—teaches us nothing. The two living species show discontinuous distribution, and are almost confined to Europe. Myogale occurs fossil in French miocene deposits, but is unknown beyond the confines of our continent. It is therefore probably of West European origin. The gap between the South Russian M. moschata and the Spanish M. pyrenaica is bridged over in so far as we know from fossil evidence that the former had a much wider range in pleistocene times, being then found in England, Belgium, and Germany. Talpa, too,—to which genus our common Mole belongs,—seems to be a West European genus, since it occurs in French miocene deposits. However, it would be difficult to name many more recent genera which could be included in the area which I propose to investigate in this chapter. The genus Lepus is probably not of Lusitanian origin, but the sub-genus Oryctolagus—to which our common Rabbit belongs—has no doubt had its original home in that region. Only two species of Lepus (Oryctolagus) are known, one of which—Lepus lacostei—has been met with in French pliocene deposits. The other is the Rabbit (L. cuniculus). Though generally considered to have been introduced into the British Islands, no reason can be brought forward in favour of such a supposition, especially as it is known to have spread into Germany in pleistocene times from South-western Europe. It occurs in France, the Spanish peninsula, North-western Africa, and on some of the Mediterranean islands. Its nearest living relatives, as we should almost expect, are found in South America.

Of the Lusitanian Birds I have already mentioned the so-called Dartford Warbler (Melizophilus undatus), which ranges from the south of England to the extreme south-west of Europe. A second species occurs on the Balearic Islands and on Corsica, Sardinia, and Sicily. The Andalusian Bush-quail (Turnix sylvatica) is probably of North African origin, and has subsequently spread into Southern Spain and Portugal, and eastward as far as Sicily. It is an instance of a migrant utilising the old Mediterranean land-connections in the opposite direction from that described in the last chapter.

Two of our British Wagtails are very closely related, so much so that it requires a very critical eye to distinguish them even at close range. They also frequently interbreed. In their distribution, however, there is a considerable difference between the White Wagtail (Motacilla alba) and the Pied Wagtail (M. lugubris). While the former ranges almost all over Europe and Asia, the latter is a local form resident in the British Islands, Southern Scandinavia, and France, and a winter visitor to Spain and North-west Africa. The genus Motacilla is probably Oriental in its origin, but it seems as if the Pied Wagtail was a Lusitanian species which had gradually spread northward, only to return to South-western Europe in severe weather for shelter.

The Bearded Titmouse (Panurus biarmicus)—the only representative of the family PanuridÆ—may possibly be a Lusitanian bird. The fact of its being absent from Scandinavia and Northern Russia is suggestive of a southern origin. It is doubtful whether the bird occurs on the south side of the Mediterranean, but it is common in the south of France and Spain, and has also been observed in Sicily, Greece, and Asia Minor. In Central Europe it is found sparingly, and eastward its range extends as far as Turkestan.

The genus Fringilla, which belongs to the great family of the Finches, appears to be not only of European origin, but, if the range of the species counts for anything, I should feel inclined to locate their home in the south-west. Altogether, five species are known. One of them, viz., Fringilla teydea, is confined to the Island of Teneriffe; another, F. madeirensis, is found in Madeira, the Canaries, and the Azores; a third, F. spodiogenys, inhabits North-west Africa. The two remaining species have a much wider range. F. coelebs—the common Chaffinch—occurs in Europe, while its range extends eastward to Western Siberia, Persia, and Turkestan. The other—F. montifringilla, known as the Brambling—is more common in Northern Europe, and generally frequents the more northern latitudes of Asia as far as Japan.

It might be urged that the peculiar little blue Magpie of Spain—Cyanopolius Cooki—should find a place among the Lusitanian species, since there is no bird like it anywhere else in Europe. But in Eastern Siberia there lives a bird so closely allied as to be barely distinguishable from it. Nevertheless, since there are some distinguishing characters, it has received a distinct name—C. cyanus. This is a most interesting and remarkable case of discontinuous distribution, which may perhaps be explained by the supposition that the genus is of Oriental origin, and has died out at its former headquarters in Southern Asia and all along the line of migration, except at the extreme limits of the range in both directions—east and west.

As we go down in the scale of life—among the lower vertebrates and invertebrates—we meet with a greater number of prominent members of the Lusitanian migration. The Bullfinch, Dipper, and Chough, which might be thought to be of Lusitanian origin, are, as I have shown in the last chapter, Asiatic.

The European snakes seem to be all of eastern origin, unless Tropidonotus viperinus might be claimed as a Lusitanian form. Of very great interest from a zoogeographical point of view is our only European member of the South American and African family AmphisbÆnidÆ. This species—Blanus cinereus—is of the size and shape of an ordinary earth-worm, from which, however, it may be distinguished by its snake-like wriggling motions. It lives under stones in Spain and Portugal, North-west Africa, and Greece. It has, therefore, a somewhat similar distribution to that of many of the animals and plants referred to in the last chapter. But here we have an animal which has evidently utilised the old Mediterranean route described on p. 271, from west to east. Two other species of Blanus inhabit Asia Minor and Syria, but most of its nearest relations either live in South America or tropical Africa. In migrating to North and West Africa, its ancestors probably made use of the land-bridge which spanned the Atlantic in early Tertiary times. Another Lusitanian Lizard—belonging not to an aberrant group, but to the typical LacertidÆ—is Psammodromus hispanicus. It is rather variable in colour—generally of a brown or green—and grows to a length at about four or five inches. It occurs throughout the Spanish peninsula and also in Southern France. One of the handsomest European Lizards, which reaches almost a foot in length,—of an olive colour with greenish or mother-of-pearl reflection, and with two yellow stripes along each side of the body,—is an allied species (P. algirus). From the Spanish peninsula it passes into Southern France and North Africa. Two other species of the genus are confined to North-west Africa.

It is quite possible that the genus Pelobates is of south-western origin. Of the two known species of this genus of Toads, one is found in the Central European plain and the other on the Spanish peninsula and in France. The closely allied Pelodytes punctatus, too, is confined to this south-western district, and their nearest relations are found in Mexico. Similarly, the genus to which the Midwife Toad (Alytes obstetricans) belongs may have its original home in that part of Europe. Of the two species, one is confined to France, Switzerland, Belgium, and Western Germany, and the other, viz., Alytes cisternasii, to Spain. Discoglossus pictus—a well-known and conspicuous Toad in Southern Europe—inhabits Spain, Algiers, and Tunis, the islands of Malta, Sicily, Sardinia, and Corsica. From the general range of the family DiscoglossidÆ, as given in Mr. Boulenger's excellent catalogue, it appears that nowhere in the vast space between China and New Zealand has any member of the family been discovered. The peculiar genus of Salamander—Chioglossa—is quite confined to the Spanish peninsula.

The Butterflies Nemeobius lucina and Charaxes jasius may also have had their home in that south-western district. To this migration also seems to belong the genus Gonepteryx, which has so peculiar a range in the British Islands. The only British species, known as the Brimstone Butterfly (Gonepteryx rhamni), occurs in the south of England and in the south and west of Ireland. It is met with over the greater part of Europe, and its range extends into Asia Minor and Northern India, and then it reappears again in distinct varieties in Japan and the Amur district. Three other species of Gonepteryx are known from Tibet and India, and one (G. cleopatra) from Southern Europe and Northern Africa. All the remaining species inhabit the west, viz., Brazil, Mexico, and Venezuela. That the genus has migrated from America eastward to Europe appears to be more probable than a migration in the opposite direction. At any rate, that an exchange of species between the south-western portion of the Holarctic Region and the Neotropical area took place is indicated by the fact, not only that a variety of G. cleopatra has been found in Madeira, but also that the Canary Islands possess a distinct form of Gonepteryx, viz., G. cleobule.

Dr. Kobelt has given us such an exhaustive memoir on the characteristic Mollusca of the different zoogeographical provinces of Europe, that we are particularly well informed as regards that group of Invertebrates. He tells us that the group Torquilla of the genus Pupa—which is a small chrysalis-like snail—is especially characteristic of the Pyrenees, Spain, and Portugal. In a certain measure they replace there the ClausiliÆ which, as we have seen in the last chapter, have come from the east and are almost entirely absent in the south-west of Europe. Of about seventy species of Torquilla, the larger number are confined to this district, and some, which like Pupa (Torquilla) granum, range eastward, have travelled along the old Mediterranean highway, vi Algiers, Sicily and Greece, to Asia Minor. They are still found along the whole of this route.

Similarly, we are told by the same author, that Gonostoma—a group of the large genus Helix—has a number of species in the same south-western district, while only one, viz., Helix obvoluta, occurs in England and Germany, and two in the Alps. Southward we again find many representatives crossing over to North Africa, among which Helix lenticula has a similar range to Pupa granum, which I have just referred to. The Alpine sub-genus Campylaea is quite absent in the Lusitanian district.

Among our own British testaceous Land Mollusca, several Helices, viz., Helix pisana, ericetorum, virgata, acuta, fusca, rotundata, aculeata, and probably many others, have come to us from the south-west. The species of Hyalinia are undoubtedly of very remote origin, and it would be futile at the present state of our knowledge to speculate as to their home. Some of our species may possibly be of British origin. Balea perversa is probably a south-western species, and certainly Pupa anglica, which is quite confined to Western Europe.

Much more characteristic of South-western Europe, however, than these land-shells are some of the slugs. The peculiar genus Geomalacus is almost entirely confined to Portugal. One species, which I have had several occasions to refer to in illustration of the term "discontinuous distribution," ranges far beyond the confines of that country. This is Geomalacus maculosus (Fig. 18), first discovered in the south-west of Ireland, and more recently also in Portugal. Although careful search has been made for it in other parts of the British Islands, this slug has only been found in the portion of Ireland just indicated. Within the last few years I have taken it, up to a height of over a thousand feet, on the promontory north of the Kenmare River, also from sea-level up to a considerable height near Glengariff, and more recently Messrs. Praeger and Welch discovered it in abundance near the town of Kenmare. But beyond this rather circumscribed area in the counties of Cork and Kerry it does not occur (vide Fig. 19). Several Portuguese species of this interesting genus have since been added to science by Dr. Simroth and others. Dr. Simroth, too, has promulgated the view that the genus Arion—to which our common brown garden slug belongs—is of Lusitanian origin. Indeed, the number of species of Arion diminishes as we leave that province, though one extends beyond the borders of Europe into Siberia. The same number of species, viz. five, occur in Germany and in England. Testacella—a slug-like mollusc—which lives underground on earthworms, and of which genus three species, viz. T. maugei, T. haliotidea, T. scutulum, are known to inhabit the British Islands, is another Lusitanian animal. All the species are confined to Western Europe and North Africa; they do not even reach Germany or Switzerland.

I have had occasion to mention once before an extremely interesting genus of blind Woodlouse, viz., Platyarthrus. Like Testacella, it lives underground, and also resembles it in its general range. Its distribution is therefore of particular interest. It is difficult to conceive that Platyarthrus, from its peculiar mode of life could have crossed any formidable barrier, such as even a narrow straits of sea. Its occurrence in Spain and North Africa indicates, therefore, that the Straits of Gibraltar did not exist at the time when it undertook the migration southward, just as the English Channel and the Irish Sea could not have been there when it wandered to England and Ireland. The species which occurs in the south of England has a wide range in Ireland, and reaches in Scotland its most northern European limit of distribution. Platyarthrus is only one of the Lusitanian genera of woodlice. In Ireland—chiefly on the west coast—we also find a brilliantly coloured Woodlouse, which is absent from Great Britain, viz. Metoponorthus cingendus. It reappears again on the Continent in the south of France. Its range is therefore suggestive of a Lusitanian origin; and indeed, when we examine the general distribution of the genus Metoponorthus, we find that out of the forty-four known species, fully one-half are confined to Western Europe and North Africa.

My friend and colleague, Mr. Carpenter, informs me that among the Irish Spiders he is acquainted with, the following are to be looked upon as Lusitanian species:—

• Dysdera crocota.
• Oonops pulcher.
• Tegenaria hibernica.
• Theridion aulicum.
• LasÆola inornata.
• Agroeca celans.
• do.gracilipes.
• Teutana grossa.
• Cnephalocotes curtus.
• Porrhomma myops.

Of the Coleoptera, the genera Trichis, Glycia, and Singilis, all belonging to the Running Beetles (CarabidÆ), are almost confined to the Spanish peninsula.

The beetles Rhopalomesites Tardyi, Eurynebria complanata, and Otiorrhynchus auropunctatus also belong to this fauna, as also the Earthworms Allolobophora veneta and A. Georgii, and the Millipede Polydesmus gallicus.

It will be evident to every one from these few instances of Lusitanian species, that somewhere in South-western Europe and North-western Africa, and also, perhaps, in a larger now submerged western land-area, there existed an active centre of development, from which animals spread in all directions.

If the presence of Platyarthrus in North-west Africa proves that the Straits of Gibraltar had come into existence after its southward migration, it also suggests that the ancestral home of this woodlouse was in the Spanish peninsula. Whether this supposition is correct or not, does not affect the Straits of Gibraltar problem, for in a migration northward into Spain from Morocco a land-connection would be equally necessary. Almost every group of vertebrates and invertebrates furnishes instances of species which must have crossed the Straits on dry land. Many naturalists have come to this conclusion, and have clearly expressed their views on the subject. At the commencement of the present period, says Mr. Bourguignat (p. 354), the north of Africa was a peninsula of Spain, the Straits of Gibraltar did not exist, and the Mediterranean communicated by the Sahara with the Atlantic.

The faunas of North-west Africa and the south-western portion of our continent are so closely related, that an uninterrupted intercourse by land must have existed for a very long period. The Mediterranean, however, throughout the Tertiary period—at any rate since miocene times—must have had almost constant communication with the Atlantic. According to Professor Suess, this was the case. The Atlantic was joined with the Mediterranean across the valley of the Guadalquivir during the Miocene Epoch, so that Andalusia must have belonged to North Africa in those days. The Straits of Gibraltar are supposed to have been formed in the next epoch. I have already expressed my disagreement with that theory from a zoogeographical point of view. The old Guadalquivir connection probably persisted much longer,—though interrupted by temporary periods of a partial retreat—so as to uncover sufficient land to allow of an interchange during miocene as well as pliocene times between the European and North African faunas. It is in this way, perhaps, that some of the members of the Alpine fauna have reached Spain by way of Corsica, Sardinia, and North-western Africa, and vice versÂ. The Balearic Islands were then connected with Spain; and we find there many curious survivals which have long ago become extinct on the mainland.

That the Straits of Gibraltar are only of recent formation has been suggested on zoogeographical evidence by Bourguignat, Simroth, Kobelt, and many others. Dr. Kobelt believes that the former land-connection between the south of Spain and Morocco was much wider than is generally assumed, and that the coast-line stretched from Oran in Algeria straight across to Cartagena in Spain (b, ii., p. 228).

My allusions to the lands lying beyond the Lusitanian province, refer chiefly to the Canary Islands and Madeira. Whatever doubts Dr. Wallace had on the subject of their former connection with Morocco, it cannot be denied that they used to be of much larger extent, especially in miocene and pliocene times. It seems extremely probable that these islands formed part of the mainland of North Africa until comparatively recently, and that they are the last traces of a sunken continent which united Africa and South America. A discussion of this problem, however, must be deferred, as it is a complicated one, and one which would lead me altogether outside the scope of this little volume. I hope I shall have an opportunity to publish my views on this subject before long, meanwhile the reader must content himself with this mere statement.

During the greater portion of the Miocene, and I think for part of the Pliocene Epoch too, the advance of the Lusitanian species eastward was barred on the continent of Europe by an arm of the sea which stretched northward along the Rhone valley from the Mediterranean. The Lusitanian forms which originated in Southern Spain were able to travel east during these times by way of North-west Africa, Sicily, Southern Italy, and Greece; it is possible that some may have reached the Alps in this manner, and Eastern Europe generally. That the Lusitanian centre was never a very active one compared with, for instance, the Oriental is indicated by many distributional facts. It is difficult to understand, however, why the Oriental species, on the whole, have migrated so far west, while few Lusitanians have gone very far east. This seems to have been noted particularly in the case of the flora. Mr. Bonnet drew attention to the fact that in Tunis there are none of the absolutely characteristic plants of Morocco and Spain, while the Oriental flora is represented by a good many species. Lusitanian species have spread chiefly southward into North Africa, and northward into France, the British Islands, and even Scandinavia. As I have mentioned in the third chapter, there are a good many species of Lusitanian origin in the British Islands. However, we have only a mere remnant of what we ought to have, had the climate been less trying. It is probable, too, that the submergence destroyed a good many plants and the insects dependent on them. That the Lusitanian fauna is very ancient in the British Islands is proved by the fact of the discontinuous distribution of so many species. A greater number survived in Ireland than in England.

Fig. 20.—The Strawberry-tree (Arbutus unedo) in its native habitat in the south-west of Ireland. (From a photograph by Robert Welch.)

Altogether—and this was strongly urged by Edward Forbes—the Lusitanian element is the oldest of the components of our fauna, and it must have poured into the British Islands for many geological periods almost without cessation. The same author, in his classic essay, refers especially to the Lusitanian flora, two prominent members of which are the British plants, Arbutus unedo (Fig. 20, p. 305) and Euphorbia hiberna (Fig. 21, p. 306). The former has a wide range in the Mediterranean region, and occurs in the British Islands only in the south-west of Ireland. The Spurge, on the other hand, is also found in the south-west of England, besides Ireland and Southern Europe.

SUMMARY OF CHAPTER VII.

The term "Lusitanian" is in this chapter employed in the wide sense, as indicating the South-west of Europe and North-western Africa. From this centre, and probably also from a now sunken land which lay to the west of it, issued a fauna and flora of which we have abundant evidence in our own islands, especially in Ireland. Edward Forbes held that the Lusitanian element of the British flora was of miocene age, and that it survived the Glacial period in this country.

At the time when the Straits of Gibraltar did not exist, and when there was free land communication between Asia Minor, Greece, and Tunis, many Oriental species migrated westward by this ancient Mediterranean route as far as Spain. They would then have invaded the more central parts of Europe from the south-west, without however being of Lusitanian origin. Of the true Lusitanian mammals a typical example is the Rabbit. Then we have a few birds and several interesting reptiles and amphibians. The genus to which the Brimstone Butterfly belongs is also of south-western origin. A number of Mollusca are mentioned which from their range likewise indicate a Lusitanian origin. Most of our British Slugs and many of our larger Snails belong to this group.

All these are merely a small remnant of what we received from South-western Europe during the Miocene and Pliocene Epochs. But they spread into many parts of Europe, and a few even crossed into Asia. The antiquity of the Lusitanian element in our fauna is especially indicated by the frequent recurrence of "discontinuous distribution" among the species belonging to that section.