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vanquished problem of zoology. How can the naturalist maintain the Arctic character of the climate which he attributes to the country of the ancient Thames in the elephant and rhinoceros period of its history!

At first sight, the presence of the elephant and rhinoceros, as natives of the Thames Valley, would suggest that a tropical climate prevailed in England in these early years of its history. The living analogues of the Thames elephant and rhinoceros are now restricted to the warm and sunny regions of the globe. Their habitat is a country of tepid waters and tropical vegetation. Leviathan,

Who lieth under the shady trees, in the covert of the reed and fens,

would seem to share with them the country of sandy desert and humid jungle and marsh. Among the fossil remains of Ilford we find associated with the animals of a class now apparently living only in hot and torrid zones, other animals now confined to the cold and frigid zones. With the rhinoceros and hippopotamus is found the mammoth, a creature whose remains have not yet been found in tropical countries, whereas they are found in abundance in northern latitudes from forty to sixty degrees. Could these creatures of apparently different geographical habitat have existed together in the ancient Thames Valley? and if so, what was the climate of the period? Perplexing as the questions appeared to the naturalists who first considered them, they are now believed to have been satisfactorily solved, without impugning or subverting the known economy of Nature. Let us look at some of the facts which help to explain the problem.

The species of elephant and rhinoceros which are first on our list (Elephas primigenus, the mammoth, and Rhinoceros tichornis, two-horned woolly rhinoceros) and which are found fossil to-day in the Thames brick-fields, had a thick coating of hair, which shows that a tropical climate was not necessary for their existence.* The elephant is still found in the cold regions of the Himalayas, with a coat of hair like that of a poodle dog.+ If Elephas primigenus were properly clothed, like its contemporaries of the early Thames Valley,

* Dr. BRANDT, quoted by PRESTWICH. † Bishop HEBER's Journal.

it might have existed as near the pole as is compatible with the growth of hardy trees and shrubs, for it was organised to gain its subsistence from the branches and woody fibres of trees, and was thereby rendered independent of the seasons which regulate the development of leaves and fruit.

The molar teeth of the elephant possess a highly-complicated and very peculiar structure, and there are no other quadrupeds that derive so great a proportion of their food from the woody fibre of the branches of trees. Many mammals browse the leaves, some small rodents gnaw the bark; the elephants alone tear down and crunch the branches, the vertical enamel-plates of their huge grinders enabling them to pound the tough vegetable tissue and fit it for deglutition. No doubt the foliage is the most tempting, as it is the most succulent part of the boughs devoured; but the relation of the complex molars to the comminution of the coarser vegetable substance is unmistakeable.

Forests of hardy trees and shrubs still grow upon the frozen soil of Siberia, and skirt the banks of the Lena as far north as latitude 60°. In Europe arboreal vegetation extends ten degrees nearer the pole, and the dental organisation of the Mammoth proves that it might have derived subsistence from the leafless branches of trees, in regions covered during a great part of the year with snow. *

It can no longer be regarded as impossible for herds of mammoths to have obtained subsistence in a country like the southern part of Siberia, where trees abound, notwithstanding that it is covered during a greater part of the year with snow, seeing that the leafless state of such trees, during even a long and severe Siberian winter, would not necessarily unfit their branches for yielding sustenance to the well-clothed mammoth.†

There is good reason to conclude that the early Thames-country, like the rest of England, may well have had a climate and flora corresponding to that of frigid Siberia. In Siberia, at the present day, the great rivers are skirted with forests of pines, alders, willows, elms, and poplars; and a northern fauna, by no means limited, shares the country with man.

But had the fossil remains of the early Thames Valley been simply and unambiguously northern in character, the naturalist and paleontologist would have pronounced an easy verdict on the phenomena before them. It is the co-existence in the ancient Thames

* Professor OWEN, op. cit.

† PRESTWICH.

K

Valley of an apparently southern fauna with those of the mammoth and Siberian rhinoceros which has yet to be fully explained. With Elephas primigenus and Rhinoceros tichornis are found not only their more southern congeners, Elephas antiquus and Rhinoceros leptorhinus, but an aquatic mollusk, which has now retreated to such waters as those of the Nile. Can these exceptional southerly fauna in the valley of the ancient Thames be so accounted for as to leave the zoology of the country mainly and characteristically of a northern type?

Here Sir Charles Lyell has supplied a provisional answer to the question. "I long ago suggested the hypothesis, that in the basin of the Thames there are indications of a meeting in the post-pliocene period of a northern and southern fauna. To the northern group may have belonged the mammoth-Elephas primigenus-and the Rhinoceros tichorhnis, both of which Pallas found in Siberia, preserved with their flesh in the ice. With these are occasionally associated the rein-deer. In 1855 the skull of the musk-ox (Bubalus moschatus) was also found in the ochreous gravel of Maidenhead, by the Rev. C. Kingsley and Mr. Lubbock; the identification of this fossil with the living species being made by Professor Owen. A second fossil skull of the same Arctic animal was afterwards found by Mr. Lubbock near Bromley, in the valley of a small tributary of the Thames; and two others were dug up at Bath Easton from the gravel of the valley of the Avon. Professor Owen has truly said, that, as this quadruped has a constitution fitting it at present to inhabit the high northern regions of America, we can hardly doubt, that its former companions, the warmly-clad mammoth and the two-horned woolly rhinoceros (R. tichorhinus) were in like manner capable of supporting life in a cold climate.'*"

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“As an example of what may possibly have constituted a more southern fauna in the valley of the Thames, I may allude to the fossil remains found in the fluviatile alluvium of Gray's Thurrock, in Essex, situated on the left bank of the river, twenty-one miles below London. The strata of brick-earth, loam, and gravel exposed to view in artificial excavations in that spot, are precisely such as would be formed by the silting up of an old river channel. Among * Quarterly Geological Journal, vol. xii. p. 124.

the mammalia are Elephas antiquus, Rhinoceros leptorhinus (R. megarhinus, Christol), Hippopotamus major, species of horse, bear, ox, stag, &c.

"We may readily conceive that the countries now drained by the Thames, the Somme, and the Seine, were, in the post-pliocene period, on the borders of two distinct zoological provinces, one lying to the north, the other to the south, in which case many species belonging to each fauna endowed with migratory habits, like the living musk-buffalo or the Bengal tiger, may have been ready to take advantage of any, even the slightest, change in their favour to invade the neighbouring province, whether in the summer or winter months or permanently for a series of years, or centuries. The Elephas antiquus and its associated Rhinoceros leptorhinus may have preceded the mammoth and tichorhine rhinoceros in the valley of the Thames, or both may have alternately prevailed in the same area in the post-pliocene period."*

No longer do the climatic varieties of zoological species—the various elephants and rhinoceri-found in the Thames Valley to-day impel us to imagine such agency as Milton has pictured for the origin of the seasons :—

Some say he bid his angels turn askance

The poles of earth twice ten degrees or more
From the sun's axle; they with labour push'd
Oblique the centric globe.

The more ordinary and imperceptible processes of Nature, in the gradual redistribution of the areas and proportions of land and water, seem adequate to account for the Arctic climate and zoology which the ancient Thames reveals to us. Many are the instances in the present terraqueous system of the earth to show that the varying distribution of land and sea is an efficient cause of abnormal climates in other latitudes than those of the Thames.

Such are the explanations of existence of elephants and rhinoceri as wild and native inhabitants of the basin of the ancient Thames.

* Antiquity of Man, pp. 156-159.

Recapitulation.

Great is the gulf that lies between the Thames of the poet and the painter, the Thames of commerce, of civic annals, of quaint mediæval life, when river sports and pageants afforded pleasant items for the chronicler, and the ancient Thames of the mammoth, rhinoceros, and hippopotamus.

In these, its declining years, the mighty creature has fallen captive to man. With shrunken bulk and in a narrower channel the Thames now winds an imprisoned course. Its vaster life and meridian years were lived before human annals began.

The Glacial Clay of Muswell Hill and the Essex Heights takes us back to the infant and aboriginal years of the Thames.

The old alluvia which strews the plains and hills for miles away from the present channel of the river tells us of the forces that excavated so great a valley and filled it with waters of commensurate volume.

The mud and the gravel of the old and deserted bed of the stream reveal to us the bones of strange and giant beasts of an old and obsolete zoological world.

The ruined slope of the southern shore tells us of the destruction by subterranean forces of the original and symmetrical valley.

The submerged forest at Plumstead tells us of revolutions in the land-surface around London, and of changes in the course of the Thames.

Far back in the "speechless past," through distant eras of zoology and terraqueous arrangement, does the auto-biography of the Thames transport us. Vast is the period we have to allow for the sequence of Nature's processes. But in the strange and startling phenomena that confront us in these homely landscapes around London, and in the new chronology they seem to demand, we find nothing to invalidate the grand assurance that

KNOWN UNTO GOD ARE ALL HIS WORKS FROM THE BEGINNING OF THE WORLD.

LONDON JUDD AND CO., PHENIX PRINTING WORKS, DOCTORS' COMMONS.

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