Page:Quarterly Journal of the Geological Society of London, vol. 28.djvu/529

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1872.]
DAWKINS—CLASSIFICATION OF PLEISTOCENE STRATA.
435

mostly of Pliocene descent, in the Forest-bed and in Rome, as well as its more southern range, it must have been better adapted for living in a temperate or comparatively warm climate than the Woolly Rhinoceros.

The third group, which was probably fitted for a temperate climate, since it occurs neither in the north nor the south of Europe, consists of

Trogontherium Cuvieri.
Machærodus latidens.
Cervus carnutorum.
C. verticornis.

Cervus megaceros.
C. Browni.
C. Sedgwictii.
C. Polignacus.

The last species, like Elephas meridionalis, is a Pliocene animal which survived into the early Pleistocene stage, and has been discovered by MM. Croizet and Jobert in the lacustrine deposit of Mont Perrier, and identified by Dr. Falconer as occurring also in the Forest-bed. Trogontherium Cuvieri and Cervus carnutorum are found alike in the Forest-bed, and the deposit of St.-Prest at Chartres, while the Machærodus latidens, of Kent's Hole, is found as far south as Auvergne and a cave in the Jura. The Irish Elk ranges, in space, from Scania as far as the valley of the Po—and in time, from the Forest-bed era down to the prehistoric peat-bogs, being far more abundant in the Prehistoric than in the Pleistocene strata. It has not, however, been discovered in the latter further north than Quedlinburg, on the Continent, and Kirkdale cave, in Great Britain, although in the prehistoric deposits of Scania it is comparatively abundant (Nilsson, MSS.).

13. The Three Climatal Zones.

The inference as to the Pleistocene climate of Europe drawn from the range of the Pleistocene species which are still living is corroborated by an appeal to those which are now extinct ; and, treating the whole mammalian land-fauna as one, we have three great climatal zones, marked out by the varying range of the animals—the northern (see Map, p. 436), into which the southern forms never penetrated, the southern, into which the northern species never passed, and an intermediate area in which the two found are mingled together. The latitude of Yorkshire is the extreme northern boundary which the southern forms never passed; and a line passing through the Alps and the Pyrenees is the limit of the range of the northern animals, properly so called. In the head quarters of the Reindeer and Musk-sheep in Scandinavia and Northern Russia, the climate must have been like that of those regions which they now inhabit; and in the head quarters of the Rhinoceros etruscus, E. meridionalis and E. antiquus, of the Spotted Hyæna, and the Hippopotamus it was most probably hot. In the following map the three zones are marked, the northern by horizontal, and the southern by vertical broken lines; while the intermediate area, in which the northern and southern animals were associated together, is represented by the crossing of the lines.