the deposition of geological formations, from the transmutation of more simple into more complex forms of organization. So also among fossil fishes, some of the earlier forms, so far from being the most simply organized, are more compound than those which followed them in the epochs of more recent secondary and tertiary formations, and than those which exist in our present seas: e. g. the saurichthys combine some of the more complex and highly organized conditions of the structure of the lizard with the more simple conditions of the fish. The nearest approximation among fossil reptiles to the character of the dicynodon occurs in the rhynochosaurus, or beaked lizard, found by Dr. Ward in the new red sandstone at Grinsill, near Shrewsbury. The rhynochosaurus is one of the many reptiles whose footsteps abound on the surfaces of strata in the new red sandstone formation. Its head, like that of birds and turtles, had no teeth. But the rhynochosaurus had no tusks; as far as we know, these organs are peculiar to the dicynodon in the family of reptiles. It is probable that the strata on which these extinct forms of reptiles have been found in the southern extremity of Africa, are coeval with the new red sandstone which contains the earliest known fossil reptiles in Europe; and which has lately afforded three species of palæosaurus at Bristol. The district in which Mr. Bain found these fossil bones, which form so interesting an accession to palæontology, is an elevated plain, nearly 200 miles wide and 600 miles long, extending north-west from Algoa bay and Graham's town, and divided by a chain of hills from the district adjacent to the Cape. The Stonesfield slate contains perhaps one of the most remarkable assemblages of organic remains that are known to geologists. Here are marine, amphibious, and terrestrial animals, associated with terrestrial, fluviatile or lacustrine, and marine plants, and with birds and insects, all collected in a bed whose greatest thickness does not exceed 6 feet. Pterodactylus, or winged lizard, one of the most extraordinary productions of the fossil world, is an animal which forms the intermediate link, hitherto deemed to exist only in fable, between birds and reptiles. This creature, previously known in two formations upon the continent, has been recently recognised in the lias of Dorsetshire. Traces of tortoises are observed in the bituminous schist of the north of Scotland, the geological situation of which is probably similar to that of the coal-measures of England. Impressions, resembling the footsteps made by tortoises, were not long since noticed on the surface of beds of new red sandstone in Dumfries-shire. Bones of several cetaceous animals occur in marine diluvium, particularly in Norfolk. They have been traced much earlier in the Stonesfield slate, in the Tilgate stone, the Kimmeridge clay, and in limestone near Bath. Their occurrence is somewhat rare with us, but less so on some parts of the continent. In Italy, entire skeletons, at 1,200 feet ele and fins. This genus exhibits the snout of a dolphin, the teeth of a crocodile, the head and sternum of a lizard, the swimmers of a whale, and the vertebrae of a fish. Found in the lias, Stonesfield slate, Oxford clay, Kimmeridge clay, coral rag or Malton oolite, and probably in other formations. The megalosaurus, or gigantic lizard of Stonesfield and Tilgate forest, is computed by Dr. Buckland to be 40 feet long. It possesses resemblances both to the monitors and the crocodiles. Mr. Mantell estimates the iguanodon, the great herbivorous reptile of the Tilgate stone, to have far exceeded the last in magnitude, and to have attained the extraordinary length of 60 feet. This appears to have been an inhabitant of fresh-water lakes and rivers. Vertebræ of another saurian animal have been discovered in the Portland series at Thame, near Oxford, of still more extraordinary dimensions. They are twice as large as those of the iguanodon, and four times the size of the vertebrae of the mastodon. Several gigantic bidental fossil lizards of extinct genera, were discovered near the Cape of Good Hope, in 1843, by Mr. A. G. Bain, of the Royal Engineers. Mr. Bain designated them bidentals, from their possessing only two teeth, or rather tusks, in the upper jaw, and none whatever in the lower jaw. Their jaws, he says, were doubtless covered with a horny serrated substance, like the turtle; and as they appear to have been aquatic reptiles, the tusks may have been used, as by the recent walrus, and extinct dinotherium, although they are smaller in proportion than those of the latter creature. The largest bidental skull might have been, when whole, of the size of the head of an hippopotamus. Professor Owen has given these bidental reptiles the generic name dicynodon, founded on the two canine tusks. He places the dicynodon in the lacertian order of reptiles. It combines in itself characters of the lizard, crocodile, and tortoise, with a form and internal structure of tusks now found only in mammalia. The tusks are placed in deep sockets in the upper maxillary bone, curved downwards nearly to a quadrant, and nourished by continuous growth from a hollow conical base like the tusks of the elephant; in all these points differing from any other reptiles, and anticipating conditions of mammalia. To these tusks in the upper edentulous jaw is added a horny mandible. The lower jaw is compounded of several bones, and, as in the turtles, without teeth, being covered with a horny case. The tusks, when examined by the microscope, are found to be composed of dentine, resembling ivory, having calcigerous tubes onetwelve-thousandth part of an inch in diameter; they do not appear to have been much worn, and were probably not used for providing food, but as weapons of offence and defence, descending from the upper jaw only, as in the living musk of Thibet, and in the extinct machairodus of Europe and America. The dicynodon, as in many recent and extinct lizards, had a small cranian cavity for the brain. Professor Owen has established three distinct species of dicy-vation. Baron Cuvier enumerates 10 fossil species. nodon, namely, D. lacerticeps, D. testudliceps, and D. strigiceps; lizard-headed, tortoise-headed, and ridgy-headed. The dicynodon appears to have been one of the first created genera of saurians, and in the composite character of its organization, especially in the condition of the tusks, exhibits in one of the earliest forms of reptiles the presence of organs which now exist only in mammals; thus showing that the most ancient reptiles were in certain parts of their structure more highly organized than any genera which succeeded them in the transitory fossil series of that great family, or than any living reptiles; and in this fact we find an addition to the many other proofs afforded by geology of the want of sound foundations in that theory of development which would derive the various species and genera of animals, that have followed one another during One is like a species native of the Ganges; a second has no close affinity with any known species; while the remaining eight bear a resemblance to the species at present natives of the British seas. Among the most remarkable additions to the fauna of the ancient world, is the colossochelys, whose remains were discovered in the Sub-Himalayan hills by Captains Cautley and Falconer. It is a gigantic fossil turtle whose length was about eighteen feet, and its height at least seven. Here was a monster creeping on feet, whose carapace or shell would have formed a respectable dining-room, and whose weight and bulk would have freighted a moderate steamer. With regard to the geological distribution of fossil quadrupeds, Baron Cuvier observed that mammiferous sea animals are in more ancient strata than mam miferous land animals; oviparous quadrupeds than viviparous quadrupeds. The oviparous quadrupeds apparently began to exist at the same time with the fishes; the land quadrupeds not until long after, and after the period when most of the shells were deposited. On comparing the antediluvian animals with those existing, it is seen that the principal loss has fallen upon the carnivora, while the ruminants are preserved. Another singular fact has been elicited through the labours of the baron. The fossil ruminants appertain precisely to the genera and sub-genera at present most common in the northern climates: to the aurochs, the musk-ox, the elk, and the reindeer; while the fossil pachydermata, the elephant, the rhinoceros, the hippopotamus, and the tapir, are limited at present to the torrid zone. Remains of carnivorous animals are frequently found in our island. The supposed antediluvian fissures of rocks, chiefly in the mountain limestone, red sandstone, and oolite, are their principal receptacles. They are derived from several extinct species of hyænas, wolf, tiger, bear, and weasel. In Yorkshire, an interesting discovery has been made of the bones of the lion and wolf mixed with those of large herbivorous animals, in lacustrine marl, beneath diluvial gravel. Baron Cuvier describes 20 or more species of fossil carnivora, including several small species from the quarries of Mont-martre. calcareous incrustations, peat formations, mines, and volcanic debris, human bones and their accompani ments have frequently been discovered, bearing evidence of very high antiquity; but they are all referable to more recent times than the deluge, and may be explained by similar events of ordinary occurrence. One of the richest deposites of fossils in Europe is in the department of Gers, at the north foot of the Pyrenees. From eight to ten thousand bones or fragments have been collected, belonging to 98 genera, sub-genera, or species of mammalia and reptiles; 91 of these were from Sansan, a village 10 miles south from Auch, and yet only about onetwentieth part of the locality has been explored. The mammalia include, 1 quadrumana (ape), 11 insectivora, 18 carnivora, 11 rodentia, 1 or 2 edentata, 21 pachydermata, 11 ruminantia, with some doubtful indications of marsupialia. The reptiles include 5 turtles, 5 saurians, 1 serpent, 3 salamanders, 6 frogs, 1 unknown genus, and I gigantic reptile. M. Lartet is of opinion that these races which occur in the upper tertiary beds were destroyed by floods descending from the Pyrenees, but less violent than those which deposited the diluvium. All the animals are of extinct species; but the remains show that moles, hedgehogs, squirrels, hares, deers, lizards, and salamanders, much less than those now existing, lived in the district with the mastodon, rhinoceros, dinotherium, the sloth, and carnivorous animals of gigantic size. No works of art, or other indications of the former existence of man, occur in diluvial or tertiary beds. We are therefore led to unite in the opinion that he is among "the most recent tenants of the globe,' coincident with the oldest records and traditions of his race; and that the time in which he has inhabited the earth forms but a trifling portion of its absolute duration. Whether man was coeval with the mastodons, the mammoths, and other mighty animals that once ranged the earth, and left their traces on so large a part of its surface, is an inquiry which there seems little probability will ever be solved. At present we have only the negative fact, that no human remains have been discovered of equal antiquity with those extinct races of animals of which we have made brief mention in this imperfect sketch. CHAP. VI. OF THE INTERNAL STRUCTURE OF THE EARTH. Herbivorous quadrupeds occupy the same geological position with the foregoing fossil mammalia. The larger animals of this class are found to possess anatomical differences from those now existing. The pachydermata are thick-skinned herbivorous quadrupeds, having more than two toes to the foot, and incisive teeth in both jaws. The Kirkdale cave has furnished bones of the elephant, thinoceros, hippopotamus, and horse. Bones of the elephant or mammoth are among the most abundant in every part of the globe. We have derived numerous specimens from Suffolk and Norfolk. The mastodon, although figured in some works on English geology, does not appear to have been authenticated as a British fossil animal. The peculiar structure of the teeth and bones of these animals has been fully illustrated in various scientific publications. An extinct quadruped of this order, named by Cuvier, anoplotherium, found in the plaster quarries of Paris, appears in a single instance to have been traced in the lower fresh-water beds of the Isle of Wight. Nearly forty species of extinct pachydermata are found in the upper deposites of the Paris environs. Among them are numerous skeletons resembling tapirs and camels, some other species of rhinoceroses and the new genus palæotheria, and three or four others. Bones of the horse are found in similar situations to the fore- HAVING, in some measure, got free from the regoing, and were therefore contemporaneous with | gions of conjecture, let us now proceed to a dethose extinct pachydermata. Remains of the ox, scription of the earth as we find it by examinathe aurochs or bison, and several species of deer, were observed in the cave of Kirkdale, and they tion, and observe its internal composition, as far occur, more or less, in all the great diluvial deposites as it has been the subject of experience, or exof this country, and in the valleys through which posed to human inquiry. These inquiries, indeed, our great rivers pass. Skulls of the Bos Urus at have been carried but to a very little depth beWalton-Naze, Woolwich, Ilford, &c. The great fossil elk of Ireland is found in peat bogs and low its surface, and even in that disquisition men gravel beds. Some of these skeletons have been have been conducted more by motives of avarice met with, although rarely, in England, at Walton than of curiosity. The deepest mine, which is and in Holderness. Cervus elaphus, or red deer; that at Cotteberg in Hungary,' reaches not more common in diluvial gravel of the eastern counties. than three thousand feet deep; but what proCervus dama, or fallow deer; traced occasionally in similar situations. Cervus capreolus, or antelope; portion does that bear to the depth of the terresnear Ipswich, and at Roydon, Norfolk.-Of the ro- trial globe, down to the centre, which is above dentia or gnawers, the Kirkdale cave alone yielded four thousand miles? All, therefore, that has to the researches of Dr. Buckland the genera hare, been said of the earth, to a deeper degree, is rabbit, rat, water-rat, and mouse. Of quadrumanmerely fabulous or conjectural: we may suppose, ous animals there exist no known traces in this or any other part of the globe, either of the ape, monkey, or the human species. In alluvial deposites, 1 Boyle, vol. iii. p. 240. constantly teased more to furnish the luxuries of man than his necessities, yet even to the last she continues her kind indulgence, and when life is over, she piously covers his remains in her bo with one, that it is a globe of glass; with ano- | the poison, she still supplies the antidote; though ther, a sphere of heated iron; with a third, a great mass of waters; and with a fourth, one dreadful volcano 5 but let us at the same time show our consciousness, that all these are but suppositions. Upon examining the earth, where it has been opened to any depth, the first thing that occurs, is the different layers or beds of which it is composed; these all lying horizontally one over the other, like the leaves of a book, and each of them composed of materials that increase in weight in proportion as they lie deeper. This is, in general, the disposition of the different materials, where the earth seems to have remained unmolested; but this order is frequently inverted; and we cannot tell whether from its original formation, or from accidental causes. Of different substances, thus disposed, the far greatest part of our globe consists, from its surface downwards to the greatest depths we ever dig or mine.6 som. This external and fruitful layer which covers the earth, is, as was said, in a state of continual change. Vegetables, which are naturally fixed and rooted to the same place, receive their adventitious nourishment from the surrounding earth and water; animals, which change from place to place, are supported by these, or by each other. Both, however, having for a time enjoyed a life adapted to their nature, give back to the earth those spoils, which they had borrowed for a very short space, yet still to be quickened again into fresh existence. But the deposites they make are of very dissimilar kinds, and the earth is very differently enriched by their continuance those countries that have for a long time supported men and other animals, having been observed to become every day more barren; while, on the contrary, those desolate places, in which vegetables only are abundantly produced, are known to be possessed of amazing fertility. "In regions which are uninhabited,"8 says Mr. Buffon, "where the forests are not cut down, and where animals do not feed upon the plants, the bed of vegetable earth is constantly increasing. In all woods, and even in those which are often cut, there is a layer of earth of six or eight inches thick, which has been formed by the leaves, branches, and bark, which fall and rot upon the ground. I have frequently observed on a Roman way, which crosses Burgundy, for a long extent, that there is a bed of black earth, of more than a foot thick, gathered over the stony pavement, on which several trees, of a very considerable size, are supported. This I have found to be nothing else than an earth formed by decayed leaves and branches, which have been converted by time into a black soil. Now, as vegetables draw much more of their nourishment from the air and water than they do from the earth, it must follow that in rotting upon the ground, they must give more to the soil than they have taken from it. Hence, therefore, in woods kept a long time without cutting, the soil below increases to a considerable depth; and such we actually find the soil in those American wilds, where the forests have been undisturbed for ages. But it is otherwise where men and animals have long subsisted for as they make a considerable consumption of wood and plants, both for firing and other uses, they take more from the earth than they return to it; it follows, therefore, that the bed of vegetable earth, in an inhabited country, must be always diminishing; and must at length resemble the soil of Arabia Petrea, and other provinces of the East, which having been long inhabited, are now become plains of salt and 8 Buffon, vol. i. p. 353. The first layer most commonly found at the surface is that light coat of blackish mould, which is called by some garden earth. With this the earth is everywhere invested, unless it be washed off by rains, or removed by some other external violence. This seems to have been formed from animal and vegetable bodies decaying, and thus turning into its substance. It also serves again as a storehouse, from whence animal and vegetable nature are renewed: and thus are all vital blessings continued with unceasing circulation. This earth, however, is not to be supposed entirely pure, but is mixed with much stony and gravelly matter, from the layers lying immediately beneath it. It generally happens, that the soil is fertile in proportion to the quantity that this putrified mould bears to the gravelly mixture; and as the former predominates, so far is the vegetation upon it more luxuriant. It is this external covering that supplies man with all the true riches he enjoys. He may bring up gold and jewels from greater depths; but they are merely the toys of a capricious being, things upon which he has placed an imaginary value, and for which fools alone part with the more substantial blessings of life. "It is this earth," says Pliny, “that, like a kind mother, receives us at our birth, and sustains us when born." It is this alone of all the elements around us, that is never found an enemy to man. The body of waters deluge him with rains, oppress him with hail, and drown him with inundations. The air rushes in storms, prepares the tempest, or lights up the volcano; but the earth, gentle and indulgent, ever subservient to the wants of man, spreads his walks with flowers, and his table with plenty; returns with interest every good committed to her care; and though she produces F sand; the fixed salt always remaining, while the | as before they got through it the workmen ceased other volatile parts have flown away." If from this external surface we descend deeper, and view the earth cut perpendicularly downwards, either in the banks of great rivers, or steepy sea-shores, or going still deeper, if we observe it in quarries or mines, we shall find its layers regularly disposed in their proper order. We must not expect, however, to find them of the same kind or thickness in every place, as they differ in different soils or situations. Sometimes marl is seen to be over sand, and sometimes under it. The most common disposition is, that under the first earth is found gravel or sand, then clay or marl, then chalk or coal, marbles, ores, sands, gravels; and thus an alternation of these substances, each growing more dense as it sinks deeper. The clay, for instance, found at the depth of a hundred feet, is usually more heavy than that found not far from the surface. In a well which was dug at Amsterdam, to the depth of two hundred and thirty feet, the following substances were found in succession: 10 seven feet of vegetable earth, nine of turf, nine of soft clay, eight of sand, four of earth, ten of clay, four of earth, ten of sand, two of clay, four of white sand, one of soft earth, fourteen of sand, eight of clay mixed with sand, four of sea-sand mixed with shells, then a hundred and two feet of soft clay, and then thirty-one feet of sand. In a well dug at Marly, to the depth of a hundred feet, Mr. Buffon gives us a still more exact enumeration of its layers of earth. "Thirteen of a reddish gravel, two of gravel mingled with a vitrifiable sand, three of mud or slime, two of marl, four of marly stone, five of marl in dust mixed with vitrifiable sand, six of very fine vitrifiable sand, three of earthy marl, three of hard marl, one of gravel, one of eglantine, a stone of the hardness and grain of marble, one of gravelly marl, one of stony marl, one of a coarser kind of stony marl, two of a coarser kind still, one of vitrifiable sand mixed with fossil-shells, two of fine gravel, three of stony marl, one of coarse powdered marl, one of stone calcinable like marble, three of gray sand, two of white sand, one of red sand streaked with white, eight of gray sand with shells, three of very fine sand, three of a hard gray stone, four of red sand streaked with white, three of white sand, and fifteen of reddish vitrifiable sand." In this manner the earth is everywhere found in beds over beds; and, what is still remarkable, each of them, as far as it extends, always maintains exactly the same thickness. It is found also, that as we proceed to considerable depths, every layer grows thicker. Thus in the adduced instances we might have observed, that the last layer was fifteen feet thick, while most of the others were not above eight; and this might have gone much deeper, for aught we can tell, 9 See Supplementary Note, p. 83. 10 Varenius, as quoted by Mr. Buffon, p. 358. digging. These layers are sometimes very extensive, and often are found to spread over a space of some leagues in circumference. But it must not be supposed that they are uniformly continued over the whole globe without any interruption; on the contrary, they are ever at small intervals cracked through as it were by perpendicular fissures: the earth resembling, in this respect, the muddy bottom of a pond, from whence the water has been dried off by the sun, and thus gaping in several chinks, which descend in a direction perpendicular to its surface. These fissures are many times found empty, but oftener closed up with adventitious substances, that the rain, or some other accidental causes, have conveyed to fill their cavities. Their openings are not less different than their contents, some being not above half-an-inch wide, some a foot, and some several hundred yards asunder. Which last form those dreadful chasms that are to be found in the Alps, at the edge of which the traveller stands dreading to look down at the immeasurable gulf below. These amazing clefts are well known to such as have passed these mountains, where a chasm frequently presents itself several hundred feet deep, and as many over, at the edge of which the way lies. It often happens, also, that the road leads along the bottom, and then the spectator observes on each side frightful precipices several hundred yards above him; the sides of which correspond so exactly with each other, that they evidently seem torn asunder. But these chasms, to be found in the Alps, are nothing to what Ovale tells us are to be seen in the Andes. These amazing mountains, in comparison of which the former are but little hills, have their fissures in proportion to their greatness. In some places they are a mile wide, and deep in proportion; and there are some others, that, running under ground, in extent resemble a province. Of this kind also is that cavern called Eldenhole, in Derbyshire, which, Dr. Plott tells us, was sounded by a line of eight and twenty hundred feet, without finding the bottom or meeting with water: and yet the mouth at the top is not above forty yards over. This immeasurable cavern runs perpendicularly downward; and the sides of it seem to tally so plainly as to show that they were once united. Those who come to visit the place, generally procure stones to be thrown into its mouth; and these are heard for several minutes, falling and striking against the sides of the cavern, producing a sound that resembles distant thunder, dying away as the stone goes deeper.12 NOTE.-Arrangement of the Strata. The following succinct account of the order of succession in which the various formations noticed in previous notes occur, their mineral composition, and characteristic fossil-remains, is taken from Mr. Richardson's work entitled Geology for Beginners.' I. Alluvium, modern and ancient; the term modern being applied to the deposites now in course of formation, or appertaining to the historic period, comprising beds of rivers, lakes, peat-bogs, coral-limestones, volcanic ejections, calcareous deposites from mineral springs, &c., containing the remains and the works of man; the latter appellation of ancient being usually bestowed on like accumulations formed prior to the historic era, and containing no vestiges of the Of this kind also is that dreadful cavern described by Elian; his account of which the reader may not have met with.13 "In the country of the Arrian Indians, is to be seen an amazing chasm, which is called The Gulf of Plato. The depth and the recesses of this horrid place are as extensive as they are unknown. Neither the natives, nor the curious who visit it, are able to tell how it was first made, or to what depths it descends. The Indians continually drive thither great multitudes of animals, more than three thousand at a time, of different kinds, sheep, horses, and goats; and, with an absurd superstition, force them into the cavity, from whence they never return. Their several sounds, how-human race. ever, are heard as they descend; the bleating of sheep, the lowing of oxen, and the neighing of horses, issuing up to the mouth of the cavern. Nor do these sounds cease, as the place is continually furnished with a fresh supply." THE TERTIARY FORMATIONS. II. A vast accumulation of various deposites, marine, lacustrine, fluviatile, and volcanic, containing plants and remains of mammalia of extinct and existmarine exuviæ, shells of the lake, river and land; ing species. SECONDARY FORMATIONS. There are many more of these dreadful perpendicular fissures in different parts of the earth; with accounts of which Kircher, Gaffarellus, and series of deposites, including strata or limestone, III. The chalk, or Cretaceous Group.-A marine others who have given histories of the wonders sandstone, marl, and clay, abounding in marine of the subterranean world, abundantly supply organic remains, plants, corals, echinodermata, molus. The generality of readers, however, will lusca, crustacea, and fish, with turtles and reptiles. consider them with less astonishment when they unique interpolation of fluviatile strata, among the IV. The Wealden Formation.-A singular and are informed of their being common all over the marine formations of the secondary period, being the earth; that in every field, and every quarry, delta of an ancient river, and comprising beds of these perpendicular fissures are to be found, ei- sandstones, limestones, and clays; containing landther still gaping, or filled with matter that has plants, fresh-water mollusca, and fish; tortoises, accidentally closed their interstices. The inat-turtles, crocodiles, and enormous reptiles, the iguanodon, hylosaurus, cetiosaurus, megalosaurus, &c., &c. tentive spectator neglects the inquiry, but their being common is partly the cause that excites the philosopher's attention to them: the irregularities of nature he is often content to let pass unexamined; but when a constant and a common appearance presents itself, every return of the object is a fresh call to his curiosity; and the chink in the next quarry becomes as great a matter of wonder as the chasm in Eldenhole. Philosophers have long, therefore, endeavoured to find out the cause of these perpendicular fissures, which our own countrymen, Woodward and Ray, were the first that found to be so common and universal. Mr. Buffon supposes them to be cracks made by the sun, in drying up the earth, immediately after its immersion from the deep. The heat of the sun is very probably a principal cause; but it is not right to ascribe to one only, what we find may be the result of many. Earthquakes, severe frosts, bursting waters, and storms tearing up the roots of trees, have, in our own times, produced them; and to this variety of causes we must, at present, be content to assign those that have happened before we had opportunities for observation. found it to consist of two compartments, the first was in shape like an oven, the other resembled the dome of a glass-house furnace. Mr. Lloyd says, from its roof were hanging stalactites, from which circumstance we may conclude, that it occurs in a limestone rock. 13 Eliani Var. Hist. lib. xvi. cap. 16. V. The Oolite. A series of marine strata, of enormous extent; comprising limestones, sandstones, fish, and reptiles, terrestrial plants, and two species and clays, replete with marine mollusca, corals, shells, of mammalia, of the marsupial order. VI. The Lias. A group of marine argillaceous limestones, marls, shales, and clays, with marine mollusca, crinoidea and fishes; wood and plants, and enormous reptiles, chiefly of the genera ichthyosaurus and plesiosaurus. VII. The Poikilitic, or variegated, or saliferous Group.-A marine formation, including marls, sandstones, limestones, and conglomerates frequently of red, and occasionally of variegated hues, containing gypsum and rock-salt, with corals, mollusca, plants, fish, and batrachian reptiles. VIII. The Carboniferous System, or coal.-Consisting of shales, clays, ironstone, sandstone, millstone-grit, and limestone, interstratified with seams of coal, containing fresh-water, and marine mollusca and fish, and innumerable remains of terrestrial and aquatic plants of tropical types, but of extinct genera and species. The mountain limestone, with some beds of shales, sandstones, and inferior coal. IX. The Devonian, or old red Sandstone System.--A marine formation; consisting of red and green marls, concretionary limestones, called cornstone, conglomerate, tilestone, micaceous, and grey sandstones, green slates, and sandstone, and blue crystalline limestone, containing corals, mollusca, and fish. X. The Silurian System.-An extensive series of marine deposites; comprising limestones, sandstones, grits, flag-stones, shales, and slates, containing corals, mollusca, crustacea (trilobites), and fish. XI. The Cambrian System.-A marine formation, comprising vast beds of slate rocks, with dark coloured limestones, and sandstones, containing two |