This is derived from the inferior rocks, the representatives in age of the Silurian formations of England; but instead of rising like these rocks in Wales and Cumberland, into lofty mountain masses, with deep, often precipitous valleys, they form only low, undulating hills, intersected by shallow river ravines, in whose banks horizontal beds of soft clay, incoherent sandstone, and slightly consolidated limestone and shale, are occasionally exposed. The lowest group consists of beds of blue clay, forming all the flat country around St. Petersburgh, and exhibiting no trace of organization except a few impressions of fucoidal plants. On this deposit rest beds of white or yellow sandstone, the intermediate sandstone of Strangways, the Ungulite grit of recent Russian observers. It is so named from the number of minute, dark, and shining fragments of the obolus or ungulite, which give to many parts of the rock a very remarkable aspect. This fossil shell, not yet found in Western Europe, varies in size from a pea to a sixpence; and to it the authors naturally paid great devotion,' regarding its fragments 'as being the most venerable animal remains of Northern • Europe. The next higher beds are the Pleta or Orthuceratite limestone, from which the greater number of the lower Silurian fossils of Russia have been collected. In the sea depositing these calcareous beds, animal life seems to have been very abundant, and they have already yielded many species of trilobites, brachiopods, and testacea, several of which were formerly known in England or Scandinavia, and have thus served to identify the formations of these countries. The evidence of fossil remains becomes more essential from the very peculiar mineralogical character of the Russian rocks, which, in their loosely aggregated condition and horizontal stratification, with hardly a trace of upheaval or metamorphism, far more resemble the tertiary and cretaceous beds filling the estuaries of Western Europe, than the old contemporary rocks of the same lands.

Next in order follows the Old Red Sandstone, or Devonian system of rocks, characterized in Russia, as in Scotland, by the remains of numerous fishes of strange forms, unknown to the modern world. Reposing on the beds just mentioned, it covers a space of 150,000 square miles, and thus considerably more than the whole British isles. No general lithological character can be given of the system. South from St. Petersburgh, it consists of red marls and sands, covered by limestone, or calcareous flags, with red or green marls and shale—the succession, indeed, varying with the locality, but such being ever the ordinary character of the beds, as seen in the river courses, where alone natural sections can be obtained. In this portion

of Russia, the Red Sandstone extends north-east to the shores of the White Sea, beyond Archangel, and down into Livonia and Courland on the west. In the Valdai hills, the Devonian strata are overlaid by carboniferous rocks, which form their south-eastern limit in the whole northern provinces. Like their predecessors, our authors thought that these beds, having once sunk below the newer formations, should not again rise to the surface in the long section south to the steppes of the Black Sea. But in one of their journeys, they found in the centre of the kingdom a broad zone of rocks, loaded with Devonian fossils, rising up in a vast dome, or lengthened axis. It is well seen in the gorges of the Oka, near Orel, and in the valley of the Don, north of Voroneje, and there consists of a light yellowish limestone, sometimes earthy, at other times impregnated with magnesia. This rock, being nowhere of a red colour, or containing much sand, more resembles the magnesian limestones of England and Germany than the equivalent Old Red of these countries. In the cliffs on the Oka, it is often concretionary, and, from the irregular disintegration, presents

a rough, sinuous, and grotesque aspect, resembling the rustic'work in the basement-story of a Florentine palace.' Though so unlike the beds of the same age further north, yet the numerous fossils—of species found also in the rocks of this age in the Boulonnais in France, in the Eifel, and in Devonshire-left no doubt of the true age of this deposit. According to subsequent observations, it seems to be also directly connected with the beds on the shores of the Baltic, formerly alluded to as the continuation of this formation in the north.

The fauna of these Russian deposits is interesting in many respects, and shows the light which facts observed in one country may often cast on the structure of another. The Old Red Sandstone of the north of Scotland has furnished very few or no shells, but a great number of fossil fishes, now well known from their description in many popular works. In Devonshire, the Eifel, and France, beds supposed of the same age contained many mollusca, but no fishes; and the fauna of these regions thus remained without any connecting link. But in Russia, this formation exhibits both the ichthyolites of Scotland, and the mollusca of the southern countries, united in the same beds; so that these two distinct classes of animals are thus proved to have been contemporary—though, for particular reasons, the fish had lived only in the northern seas of Caithness and Forfarshire, the shells only in the more southern waters of Devonshire and the Boulonnais. It is no less remarkable, that many identical species should occur in rocks so widely distant;

though even at the present time many similar facts are known. It is also curious to observe how the same tribes seem to have preferred a sea of the same nature even in these widely-separated regions--the fishes leaving their remains among sands and clays, the mollusca in the finely laminated limestones; whilst on the flanks of the Ural, where beds of this age, but more calcareous in character, again appear, the Polypifers, or coral-building races, have especially abounded.

Among the specimens of fishes from Russia submitted for examination to Agassiz, that distinguished ichthyologist found eight or ten species common also to the Old Red Sandstone of Scotland, and describes the identity as so complete, 'that the specimens of the two countries resemble each other to the 'extent of being confounded, often appearing to be the very casts of each other.' Among these is one gigantic monster of the ancient ocean, the Chelonichthys Asmusii; fragments of which, found in Scotland, could only be rightly interpreted from the more perfect specimens brought from Russia. At one time, these remains were thought to belong to some Saurian reptile, one bone measuring even two feet nine inches in length. But with this identity of certain species there is also a diversity in others, some forms most characteristic of the Scottish strata having never been found in Russia, and some of its races, again, being unknown in our islands; thus showing that the same great laws which, in our days, assign to each region of the globe its appropriate inhabitants, also prevailed in those remote ages.

The next higher formation in Russia, as in other parts of Northern Europe, is the carboniferous system, covering a district scarce inferior in extent to the Devonian rocks. From the shores of the White Sea, south to the Valdai Hills, it is seen overlying the older beds in many natural sections, and from this ridge spreads out to the east and south beyond Tula and Riazan, forming the whole upper basin of the Volga, and the plateau that gives birth to the Don, Dnieper, and Dwina, rivers flowing in the most divergent directions to the most widely-separated seas--to the Caspian, the Sea of Azof, the Euxine, and the Baltic. This formation in the lower part consists of sand and shales, and above, chiefly of grey, white, or yellow limestones, sometimes dolomitic, at other times with layers of Aint. It also contains occasional beds of bituminous shale, and a few seams of coal, but neither in much abundance, nor of a good quality. It is generally very pyritous, impure, fragile, and light, and seldom equals in quality the best lignites of the tertiary age in the Alps. Like the strata in which it lies, the coal seems never to have been fully mineralized; so

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that the sands, in fact, are often as incoherent as the dunes of a sea-shore; the shale is mere blue clay, and the associated

lignite is naturally light and impure, representing the first and “second stages only in the chemical change which plants undergo

in their transition into coal.' It is remarkable that the only fossil plant observed in this deposit was the Stigmaria ficoides, so abundant in the coal-fields of our own country and of North America, and which, there is now reason to believe, is only the gigantic creeping root whence sprung the vast forests, whether of Sigillaria or other trees, whose accumulated remains now yield the almost inexhaustible stores of fossil fuel. In the limestones, many corals, productæ and other shells, occur, the species being often identical with those in the mountain limestone of our own islands.

In the south of Russia, between the Donetz and the stripe of tertiary beds forming the immediate shore of the Sea of Azof, another smaller, but more valuable, deposit of carboniferous strata exists. It is bounded on the east by the granitic steppe which extends from Marsupol on the Sea of Azof, by the cataracts of the Dnieper, in a broad tract between that river and the upper course of the Bug, into Volhynia. The igneous

. forces acting in this region have produced more disturbance and dislocation in the adjoining coal-field, than is usual in Russian formations, and have thus exposed more instructive sections. The mass of the deposit consists of shales, sandstones, and limestone, with beds of coal. On the southern slope, towards the sea, the latter are thin, and from being bituminous on the west, change gradually to anthracite on the east. In the north, on the Donetz, some richer seams of coal occur, which were first worked by the Scottish miner, Gascoigne, whose name has acquired a permanent place in Russian history, as the earliest explorer of some of the most important sites of iron-ore and coal, and as having established many of the great iron foundries. Though no English workmen are now found in the mines, yet some of the names they imposed on the different beds—as main, splent, cherry coal-still remain in use. The most important mines are those of LissitchiaBalka, where seven seams of coal are wrought for use; and thirteen, some of small dimensions, are known in all. In a vertical depth of 900 feet, the coal seams compose upwards of 30 feet, the limestones 50, the grits and sandstone above 200, the remainder consisting of various qualities of argillaceous strata. In several beds, from top to bottom of the mass, fossil marine shells occur ; whence the author draws the conclusion that in this field, at least, the coal does not consist of plants

which grew on the spot, but of ancient vegetation, borne by rivers into the ocean. Sir R. Murchison is inclined to believe that a large amount of valuable coal exists in this region, and that it may yet, as in many parts of England, be found extending in unbroken masses below the newer rocks in the vicinity.

On the western declivity of the Ural, a narrow band of rocks of this epoch extends from the point where the river of that name leaves the chain, almost to its termination in the Arctic Sea. We cannot stop to describe these beds in detail, but shall conclude our account of the carboniferous formation by stating the important fact, that whilst its fauna contains numerous forms, identical with those in deposits of the same age in the British Isles and North America, it also presents so many points of diversity, that we cannot admit the conclusion of the author, that it proves "conditions of equable climate to have prevailed with great intensity over enormous areas.' The facts he has collected show that many of the species, perhaps even the genera, were different, and that some families of animals, as the cephalopods and encrinites, so common in similar beds in Western Europe, were very rare in Russiafacts more consistent with diversity of climate, like that now existing on the earth, than with great uniformity. Considerable similarity of climate and fossils might, however, reasonably be looked for, as Moscow and Edinburgh are almost in the same latitude, and the great mass of the carboniferous rocks of the two countries is included within the same parallels.

The next higher deposit, corresponding to the Magnesian limestone of England, the Zechstein of Germany, has been named the Permian by Sir R. Murchison, as largely displayed in the ancient kingdom of Perm. It is the most extensive formation in the Russian empire, filling the whole upper basin of the Dwina, whence it extends east over the wide valley of the Kama to the base of the Urals, which it follows, without penetrating into the chain, to their extremity below Orenburg; whilst on the south-west it includes the whole banks on both sides of the Volga, from where it turns east, after joining the Mologa, to below Kazan, where the mighty river is again'deflected to the south. Through this vast region the substratum consists of nearly horizontal beds of very varied mineral ' aspect, of grits, sandstones, marls, conglomerates, and lime

stone, sometimes inclosing great masses of gypsum and rock "salt, and also much impregnated with copper, and occasionally ' with sulphur, yet the whole group characterised by one type * only of animal and vegetable life. With the latter, the copper ore seems very closely connected; so much so, that the dis

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