Perhaps in all the physical geology of England there is nothing finer than the erupted heights of the Clee. Encircled by the typical “Old Red”—a wide-stretching tract of alternating sandy shores and gravel-beaches of that period—are the characteristic beds of the coal-measures, lying upon Millstone Grit and Mountain Limestone.

Of the causes that have elevated these deposits into the hills of Titterstone and the Brown Clee I need not speak—their basaltic summits, where the erupted rock has assumed a rude columnar form after cooling, are sufficient evidence; but I would direct especial attention to that group of beds whose strike is along the Oreton ridge, and whose chief member, the Mountain Limestone, forms its axial line. This lies midway between the two hills; its southern side slopes down the “Common,” and is composed of Millstone Grit, cut off abruptly by a long line of fault, the effect of which has been to have depressed that deposit into a valley, and to have raised the underlying “Old Red” into a nearly continuous line of cliff. The accompanying section will better describe their relative positions.

These Millstone Grits are non-fossiliferous; but the mineralogist may detect in their conglomerated structure many pebbles of a high class, jaspers and cornelians of pure quality being often met with. These beds lead up to the Mountain Limestone, which contains a fine series of organic remains, such as palatal teeth of the Cestraciont fishes. Petalodus Hastingsii and Psammodus porosus are abundant; yet, although fragments of their jaws are not uncommon, I have only met with one specimen having the teeth in their true position.

In my former paper I endeavoured to describe the general appearance and characteristics of the limestone, millstone grit, and Pennant rocks of this coal-field, and shall now proceed to give a brief outline of the coal measures themselves and their fossil contents. As I stated before, the character of the coal is materially different in different parts of the basin; for instance, if a line be drawn from Merthyr to the sea in a south-western direction, it will divide the basin into two unequal portions, the eastern one containing bituminous coal, and the western the anthracite. I do not mean to say that there is an exact line of demarcation between the two kinds of coal, but merely that such a boundary will seem to show pretty well where the two qualities pass into one another. Curiously enough, too, in the western or anthracite portion the seams are anthracitic in the northern bassets, while the southern outcrops of the same veins are bituminous. The anthracite is now in very great demand; but, formerly, people would have nothing to do with it, and there was even a law passed to prevent its being burned in London, on account of its supposed noxious qualities, and the idea that it was detrimental to health. It differs from the bituminous coal principally in containing more carbon, less bituminous matter, and less ashes; and, as a consequence, is a much cleaner-burning coal. We may, however, dismiss the anthracite, as this portion of the field is destitute of it.

Searching for coal is, not only at home but also abroad, a serious subject, and one in which the practical utility of connecting geological knowledge with active operations is particularly obvious, and which from actual experience I can well illustrate by many interesting cases which have come under my own notice. The first determinations in a coal “adventure” may be classified as follows:—

1. Where coal is not. 2. Where coal may be, but at too great a depth for working. 3. Where coal may be found convenient for working. 4. Its quality and extent.

In order to make what follows the more interesting, we may premise, what every Geologist now knows—that the earth is made up of strata of different kinds—e.g., sandstones, limestones, and argillaceous beds called rocks. The different strata have been formed step by step, layer upon layer. Each stratum has its distinct position and age in relation to other strata. The relative age and, consequently, position of a rock can be distinguished by mineral structure, fossil contents, or both.

Again, by way of still more clearly establishing our primary position, let the following table represent some of the strata above and below the general coal deposit:—

Now this partial table of British strata represents the coal measures as being overlaid by the New Red Sandstone deposits, and underlaid by the Mountain Limestone and Old Red Sandstone, which, though a general, is by no means the invariable rule in coal deposits, as sometimes the Mountain Limestone is absent, and the coal measures rest upon the old red system, as in great part of the Shropshire coal-field.

But what are the silent voices of the past saying—for what have the wonderful and mysterious powers of nature for so many ages been labouring? Where, through all the strange mysteries of the past, is the finger of God pointing? To MAN, and the world that is his. Look at all the appropriations of every kind of organic and inorganic matter to such varied and different purposes by our race, and can we divert our minds from contemplating the vast time and the numberless operations which have assisted in the elaboration of the materials necessary for our comforts or our wants? Past and present creations alike show that animals fitted for each peculiar condition of our planet have existed at every period; but of all those classes which have passed away, or of those which exist, there are none which have not been limited in their geographical range, none to which a considerable other portion of this world has not been useless and unserviceable. Is it so with man? The stars of heaven—how many ages old!—tell him the track of the world he lives upon; mysterious magnetism guides the slender needle by which his freighted ships are safely steered from shore to shore; the very lightning is his messenger. The coal and iron of his mighty engines are ages old; the clay of the bricks of which he builds his houses, and the marble of the statues with which he adorns his palaces, have passed through ages of preparation; innumerable and diversified as are the materials of the earth, has he not a use for them all, from the lowermost granites to the uppermost surface-soils?

The Palæozoic System comprises the earliest fossil-bearing strata. These have collectively a great thickness, and are of various mineral characters, being argillaceous, arenaceous, and calcareous, generally indurated, and occasionally metamorphosed.

As a general rule, these strata appear in the western and north-western districts of Britain, and, to a considerable extent, in the mari-time districts of Ireland. The rocks of this system contain the chief metaliferous workings, as in Cornwall, North Wales, Cumberland, Scotland, &c. The upper portion, namely, the Carboniferous, affords the chief source of our lead-ores which occur in the limestone of Derbyshire, Flintshire, and Cumberland; and the associated shales and sandstones, forming the Coal-Measures, contain the well-known extensive deposits of fossil fuel and iron-ore.

The palæozoic strata are numerous enough and sufficiently distinct among themselves to form several series. The first or lower of these comprises the Cambrian and Silurian; the middle is the Devonian; and the uppermost includes the Carboniferous and Permian.

The lower portion of the palæozoic system has two great groups of rocks; the lower one is named Cambrian by the Rev. Professor Sedgwick,—from its great extent in Wales;—the other is called Silurian by Sir Roderick Murchison, on account of the typical strata of this group having been worked out by him in the country once inhabited by the Silures,—the border-counties of England and Wales, where the group is extensively developed.

Of all the wondrous changes which nature has wrought on the earth's crust, there is scarcely anything that will bear comparison with those which meet the eye of the traveller in volcanic regions. Of the two great agents in. Geological transformation—water and fire, the one moves us with admiration at the delicacy of its operations, the other strikes us with awe at the mightiness of its influences, and the rapidity of its work.

Few, if any, countries present ua with such remarkable or various manifestations of the potency of subterranean heat as Iceland. So much so, indeed, that it appears as though it were the acknowledged safety-valve, in this portion of our globe at least, through which the troubled contents of depths unknown may, on any emergency, find a ready vent.

Interest more than ordinary appears to have been taken of late in this most remarkable region. No less than six parties of tourists having, during the year before last, investigated the natural marvels of the island. One of these adventurers, Lord Dufferin, in a most interesting and amusing book, has given to the world a record of his travels. From his “Letters from High Latitudes” we propose to quote his graphic picture of the result of volcanic action, in producing a very remarkable and very manifest change in the aspect of the large tract of country to which that portion of hiB narrative refers.

But before we proceed to this, it may perhaps be useful to recal to the reader's recollection the two theories which have, up to the present time, been put forth with respect to the causes of internal heat, and hence to the origin of volcanic action in general.

The crinoids, which in this paper I bring under notice, belong to two new genera, which I have designated, the one by the name of Hydreionocrinus (ὑδρϵῖον, a watering-pot), from the resemblance to the rose of a watering-pot of the head of the species referred to, and the other by the name of Pisocrinus (πίσον, a pea). I begin with the exposition of the character of these new genera, and will afterwards describe the species which belong to them, and in doing this I shall make use of the same technical terms as I have done in my other works upon the crinoids.

Genus.—Hydreionocrinus, De Koninck.

Synonyms.—Poteriocrinus (in part), Phillips, 1836, “ Geol. of York,” Vol. II., p. 204.

Cupressocrinus, M'Coy, 1849, Ann. Nat. Hist.,” 2 ser., Vol. II., p. 22 4; non Goldfuss.

Poteriocrinus, De Kon., 1854, “Recherches sur les Crinoides,” p. 90.

Generic Formula.—Basal plates 5, Sub-radial plates 5, of which three are of the same form, the fourth serving as a base to one radial, and the fifth welded to two anals; Anal plates 5; Radial plates 2 × 5, of which one reposes directly on one of the sub-radials; Brachial, or arm-plates, 5 × 10, giving rise to 20 arms, welded together, and composed of alternating articulations, to the number of 18 or 20, and surmounted by a circle composed of 15 fusiform pieces, joined to each other. Vault or dome, composed of a great number of little pentagonal or hexagonal pieces. Stem with cylindrical articulations.