Classification of Pleistocene Strata by means of the Mammalia.—The late, middle, and early Pleistocene Divisions.—The Pleiocene Mammalia.—Summary of characteristic Pleiocene and Pleistocene Species.—Antiquity of Man in Europe.—Man lived in India in Pleistocene Age.—Are the Pal?olithic Aborigines of India related to those of Europe?—Pal?olithic Man lived in Palestine.—Conclusion.

The animals inhabiting the caves have been enumerated in the last three chapters, and we have discussed the inferences drawn from their distribution as to the pleistocene climate and geography of Europe. It remains for us now, in conclusion, to define the pleistocene, and to see in what relation it stands to the pleiocene period.
Classification of Pleistocene Strata by means of the Mammalia.

The pleistocene period was one of very long duration, and embraced changes of great magnitude in the geography of Europe, as we have seen in the ninth and tenth chapters. The climate, which in the preceding pleiocene age had been temperate in northern and middle Europe, at the beginning of the pleistocene gradually passed into the extreme arctic severity of the glacial413 period. This change caused a corresponding change of the forms of animal life; the pleiocene species, whose constitutions were adjusted to temperate or hot climates, yielding place to those which were better adapted to the new conditions. And since there is reason for the belief that it was not continuous in one direction, but that there were pauses or even reversions towards the old temperate state, it follows that the two groups of animals would at times overlap, and their remains be intermingled with each other. The frontiers also of each of the geographical provinces must naturally have varied with the season; and the competition for the same feeding-grounds between the invading and retreating forms must have been long, fluctuating, and severe. The passage, therefore, from the pleiocene to the pleistocene fauna might be expected to have been extremely gradual in each area. The lines of definition between the two are to a great extent arbitrary, instead of being marked with sufficient strength to constitute a barrier between the tertiary and post-tertiary groups of life of Lyell, or between the tertiary and quaternary of French geologists. The principle of classification which I have proposed267 is that offered by the gradual lowering of the temperature, which has left its mark in the advent of animals before unknown in Europe; and according to it I have divided the pleistocene deposits into three groups.

1. Those in which the pleistocene immigrants had begun to disturb the pleiocene mammalia, but had not yet supplanted the more southern animals. No arctic mammalia had as yet arrived. To this group belongs the forest-bed of Norfolk and Suffolk, and the deposit at St. Prest, near Chartres.

414 2. That in which the characteristic pleiocene deer had disappeared. The even-toed ruminants are principally represented by the stag, the Irish elk, the roe, bison, and urus. Elephas meridionalis and Rhinoceros etruscus had retreated to the south. To this group belong the brick-earths of the lower valley of the Thames, the river-deposit at Clacton, the cave of Baume in the Jura, and a river-deposit in Auvergne.

3. The third division is that in which the true arctic mammalia were among the chief inhabitants of the region; and to it belong most of the ossiferous caves and river-deposits in middle and northern Europe.

These three do not correspond with the preglacial, glacial, and postglacial divisions of the pleistocene strata, in central and north Britain; since there is reason to believe that all the animals which occupied Britain after the maximum cold had passed away, had arrived here in their southern advance before that maximum cold had been reached; or, in other words, were both pre- and postglacial.

This classification does not apply to pleistocene river-strata south of the Alps and Pyrenees, into which the arctic mammalia never penetrated.
The Late Pleistocene Division.

The late pleistocene division corresponds in part with the reindeer period of M. Lartet; but it comprehends also his other three periods; for the spotted hy?na, the lion, the cave-bear, the mammoth, the woolly rhinoceros, the bison, the reindeer, and the urus are so associated together in the caves and river deposits of Great Britain and the continent that they do not afford a means of415 classification. The arctic division of the mammalia, defined in the preceding chapter, was then in full possession of the area north of the Alps and Pyrenees, and the Rhinoceros megarhinus and Elephas meridionalis had disappeared. With three exceptions, to be noticed presently, all the ossiferous caverns of France, Germany, and Britain, belong to this division of the pleistocene.
The Middle Pleistocene Division.

The middle division of the pleistocene mammalia may now be examined, or that from which the characteristic pleiocene deer had vanished, and were replaced by the invading forms from the temperate zones of northern Asia. It is represented in Britain by the mammalia obtained from the lower brick-earths of the Thames valley, at Crayford, Erith, Ilford, and Gray’s Thurrock, by those from the deposit at Clacton, and most probably by those of the older deposit in Kent’s Hole, and by the Rhinoceros megarhinus of Oreston.268 They consist of—

Man, Homo.
Lion, Felis leo spel?a.
Wild Cat, F. catus.
Spotted Hy?na, Hy?na crocuta var. spel?a.
Grizzly Bear, Ursus ferox.
Brown Bear, U. arctos.
Wolf, Canis lupus.
Fox, C. vulpes.
Otter, Lutra vulgaris.
Urus, Bos primigenius.
Bison, Bison priscus.
Irish Elk, Cervus megaceros.
Stag, C. elaphus.
Brown’s Fallow Deer, C. Browni.
Roedeer, C. capreolus.
Musk Sheep, Ovibos moschatus.
Elephas antiquus.
Mammoth, E. primigenius.
Horse, Equus caballus.
Woolly Rhinoceros, Rhinoceros tichorhinus.
R. hemit?chus.
R. megarhinus.
Wild-boar, Sus scrofa.
Hippopotamus, Hippopotamus amphibius.
Beaver, Castor fiber.
Water-Rat, Arvicola amphibia.

416 The discovery of a flint-flake in the undisturbed lower brick-earths of Crayford, by the Rev. O. Fisher, in the presence of the writer, in April 1872, proves that man was living while these fluviatile strata were being deposited.

If these mammalia be compared with those of the forest-bed or the pleiocene age on the one hand, and with the late pleistocene on the other, it will be seen that they are linked to the former by Rhinoceros megarhinus, and to the latter by the musk sheep. The presence of the latter, the most arctic of the herbivores, in such strange company is most abnormal, and suggests the idea that the remains belong to two distinct eras. The skull, however, which I found at Crayford in 1867, and presented to the Museum of the Geological Survey, rested in intimate association with the bones of other species, is in the same mineral state, and bears no marks of being a “derived fossil.” It is the only trace of the animal as yet obtained from the lower brick-earths.

The absence of the reindeer, so numerous in the valley of the Thames, while the late pleistocene strata were being accumulated by the river, and the abundance of remains of the stag, seem to me to point backwards rather than forwards in time, and to imply that the lower brick-earths are not of late pleistocene age; just as the absence of the characteristic early pleistocene species shows that they are not of that age. The evidence seems to be sufficient to establish a stage intermediate between the two. Nevertheless, it is sufficiently conflicting to cause Dr. Falconer to come to the conclusion that these strata are of pleiocene date, and Mr. Prestwich to believe that they belong to a late stage in the pleistocene.

417 During the middle pleistocene, in the Thames valley, and at Clacton, the woolly rhinoceros, elephant, and mammoth competed for the same feeding-grounds with Rhinoceros hemit?chus, R. megarhinus, hippopotamus, and Elephas antiquus. Although all the characteristic pleiocene deer had retreated, the reindeer had not yet invaded that area: it was occupied by the stag, roe, the Irish elk, and Brown’s fallow deer. The whole assemblage of animals, the musk sheep being excepted, implies that the climate was less severe at this time, than when the reindeer spread over the same area in the late pleistocene age, and was far more numerous than the stag. It may, indeed, be objected that the classificatory value of the musk sheep is quite as great as that of Rhinoceros megarhinus; but in the case of the lower brick-earths, the evidence of the latter as to climate agrees with that of the whole assemblage of animals, while that of the former is altogether discordant.

There are no caves either in Britain or on the continent which can be referred with certainty to this middle division. The machairodus, however, of Kent’s Hole, and of the cavern of Baume in the Jura (see p. 337), and the megarhine species of rhinoceros from the fissures of Oreston, probably inhabited those regions, while the temperate group of animals held possession of the valley of the Thames, and of that now sunk beneath the North Sea.
The Early Pleistocene Mammalia.

The fossil mammalia must now be examined, which inhabited Great Britain during the early pleistocene period, and before the maximum severity of glacial cold had as yet been reached. The fossil bones from the418 forest-bed, which underlies the boulder-clay on the shores of Norfolk and Suffolk, have for many years attracted the attention of naturalists and geologists. The magnificent collections of the Rev. John Gunn, and the late Rev. S. W. King, gave Dr. Falconer the means of proving that the fauna of the ancient submerged forest differed from that of any geological period which we have hitherto discussed: and the careful diagnosis of all the fossils from this horizon which I have been able to meet with, shows that it was of a very peculiar character, being closely allied to the pleiocene of the south of France and of Italy, and yet possessing species which are undoubtedly pleistocene. The following list is necessarily very imperfect, since the fragmentary nature of the fossils renders a specific identification very hazardous; and it only includes those which I have been able to identify with any degree of certainty.

Sorex moschatus.
S. vulgaris.
Talpa Europ?a.
Trogontherium Cuvieri.
Castor fiber.
Ursus spel?us.
U. arvernensis.
Canis lupus.
C. vulpes.
Machairodus.
Cervus megaceros.
C. capreolus.
C. elaphus.
Cervus Polignacus.
C. carnutorum.
C. verticornis.
C. Sedgwickii.
Bos primigenius.
Hippopotamus major.
Sus scrofa.
Equus caballus.
Rhinoceros etruscus.
R. megarhinus.
Elephas meridionalis.
E. antiquus.
E. primigenius.

From the examination of this list, the peculiar mixture of pleiocene and pleistocene species is evident. The Ursus arvernensis, Cervus Polignacus, Hippopotamus major, Rhinoceros etruscus, and R. megarhinus, the horse,419 Elephas meridionalis, and E. antiquus were living in the pleiocene age in France and Italy, and probably in Norfolk. The cave-bear, the wolf, fox, mole, beaver, Irish elk, roe, stag, urus, wild-boar, and the mammoth have not as yet been discovered in the continental pleiocenes, as judged by the standards offered by the Val d’Arno and Southern France. They are more or less abundant in the late pleistocene age. This singular association seems to me to imply that the fauna of the forest-bed is intermediate between the two, and, from the fact that only three out of the whole series, viz. Ursus arvernensis, Rhinoceros etruscus, and Cervus Polignacus, are peculiar to the continental pleiocene, that it is more closely allied to the pleistocene than to the pleiocene.

It is also very probable that this early pleistocene age was of considerable duration; for in it we find at least two forms (and the number will probably be very largely increased) which are unknown in continental Europe, although pleiocene and pleistocene strata have been diligently examined in France and Germany. The very presence of the Cervus Sedgwickii and C. verticornis implies that the lapse of time was sufficiently great to allow of the evolution of forms of animal life hitherto unknown, and which disappeared before the middle and late pleistocene stages. The Trogontherium also, as well as the Cervus carnutorum, both of which occur in the forest-bed and in the gravel-beds of St. Prest, near Chartres, and which are peculiar to this horizon, point to the same conclusion.

The deer of the forest-bed, in this list, do not represent approximately the number of species: there are at least five, and perhaps six, represented by a series of antlers, which I do not venture to quote, because I have420 not been able to compare them with those of the pleiocenes of the Val d’Arno, of Marseilles, or of Auvergne.

Dr. Falconer pointed out that one of the peculiar characters of the fauna of the forest-bed is the presence of the mammoth; and the evidence on which he considered the animal to be of preglacial age in Europe has been fully verified by the molars from Bacton, which are now in the Manchester Museum. They are associated with Elephas meridionalis and E. antiquus, and are incrusted with precisely the same matrix as the teeth and bones of those species.

No caves have been discovered containing this peculiar assemblage of fossil animals.
The Pleiocene Mammalia.

The relation of the pleistocene to the pleiocene fauna is a question of very great difficulty, because the latter has not yet been satisfactorily defined, although Prof. Gervais and Dr. Falconer have given the more important species from Auvergne, Montpellier, and the Val d’Arno. The following list is taken from Prof. Gervais’s great work “Zoologie et Paléontologie Fran?aises,” p. 349, the term pseudo-pleiocene merely implying that the fauna differs from that of the marine deposit of Montpellier, which he takes as his standard.
Pseudo-pleiocene of Issoire.

Hystrix refossa.
Castor issiodorensis.
Arctomys antiqua.
Arvicola robustus.
Cervus pardinensis.
C. arvernensis.
C. causanus.
421Sus arvernensis.
Lepus Lacosti.
Mastodon arvernensis.
Tapirus arvernensis.
Rhinoceros elatus?
Bos elatus.
Cervus polycladus.
C. ardens.
C. cladocerus.
C. issiodorensis.
C. Perrieri.
C. etueriarum.
Ursus arvernensis.
Canis borbonidus.
Felis pardinensis.
F. arvernensis.
F. brevirostris.
F. issiodorensis.
Machairodus cultridens.
Hy?na arvernensis.
H. Perrieri.
Lutra Bravardi.

To these animals Dr. Falconer269 adds Hippopotamus major, Elephas antiquus, and Rhinoceros megarhinus, and he identifies Rhinoceros elatus with his new species Rh............