The History of the European Fauna Part 13

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 (_Talpidae_)--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 t.i.tmouse (_Panurus biarmicus_)--the only representative of the family _Panuridae_--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. clebs_--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 lat.i.tudes of Asia as far as j.a.pan.

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. cya.n.u.s_.

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 _Amphisbaenidae_. This species--_Bla.n.u.s 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 _Bla.n.u.s_ 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 Lacertidae--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 pa.s.ses 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 _Discoglossidae_, as given in Mr. Boulenger's excellent catalogue, it appears that nowhere in the vast s.p.a.ce 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 b.u.t.terflies _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 b.u.t.terfly (_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 j.a.pan 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 _Clausiliae_ 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, _via_ 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.

[Ill.u.s.tration: Fig. 18.--The Spotted Slug (_Geomalacus maculosus_).]

Much more characteristic of South-western Europe, however, than these land-sh.e.l.ls 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 ill.u.s.tration 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 circ.u.mscribed 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.

[Ill.u.s.tration: Fig. 19.--Map of the British Islands on which the geographical distribution of _Geomalacus maculosus_ is indicated in black.]

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 aulic.u.m.

Lasaeola 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 (_Carabidae_), 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 versa_.

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 a.s.sumed, 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.

[Ill.u.s.tration: Fig. 20.--The Strawberry-tree (_Arbutus unedo_) in its native habitat in the south-west of Ireland. (From a photograph by Robert Welch.)]

[Ill.u.s.tration: Fig. 21.--The Irish Spurge (_Euphorbia hiberna_) in its native habitat in the south 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 cla.s.sic 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 b.u.t.terfly 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.

CHAPTER VIII.

THE ALPINE FAUNA.