one individual indicate an animal between three and four feet long; the teeth seem to have been of an advanced character for the class, that is, fixed in distinct alveoli, and the animals were furnished with weak limbs serving only to swim or creep. may be remarked that the labyrinthodonts were at first thought to belong to the batrachian order (frogs and toads), but are now considered as members of the Saurian order,-that of which crocodiles and lizards are the modern representatives. They are supposed to have been "Saurians arrested in their development, on the level of the batrachians," furnishing "a proof that representatives of a permanent larva condition existed among the loricated reptiles of the ancient world, in the like manner as the sirens do among the recent batrachians."

Coal strata are nearly confined to the group termed the carboniferous formation. Thin beds are not unknown afterwards, but they occur only as a rare exception. It is therefore thought that the most important of the conditions which allowed of so abundant a terrestrial vegetation-whatever these were had ceased about the time when this formation was completed.

The termination of the carboniferous formation is marked in some regions by symptoms of great disturbance. Coal-beds generally lie in basins, as if following the curve of the bottom of seas. There is no such basin which is not broken up into pieces, some of which have been tossed up on edge, others allowed to sink, causing the ends of strata to be in some instances many yards, and in a few, several hundred feet, removed from the corresponding ends of neighbouring fragments. These are held to be results of volcanic movements below, the operation of which is further seen in numerous upbursts and intrusions of fireborn rock (trap). That these disturbances took place about the close of the formation, and not later, is shown in the fact of the next higher group of strata being comparatively undisturbed. Other symptoms of this time of violence are seen in the beds of conglo

1 Quarterly Journal Geol. Soc. Nov. 1848.

merate which occur amongst the first strata above the coal. These, as usual, consist of fragments of the elder rocks, more or less worn from being tumbled about in agitated water, and laid down in a mud paste, afterwards hardened.' It is to be admitted for strict truth, that in some parts of Europe the carboniferous formation is followed by superior deposits, without the appearance of such disturbances between their respective periods; but such cases apparently are exceptive.

PERMIAN ERA. REPTILES.

In this subordinate manner may be noticed a short series of strata, following, whether conformably or otherwise, upon the carboniferous formation, and to which a general name has been applied, from its being unusually well developed in the portion of Russia which formed the ancient kingdom of Permia. This sub-formation-comprehending in ascending order a group of sandstones, called with us the Lower New Red Sandstones, and amongst the Germans Rothe-todteliegende'-a thick calcareous bed called with us the Magnesian Limestone, by the Germans Zechstein,-and some other strata-is, in respect of fossils, a continuation of the carboniferous system. With it, however, ends a range of animal forms which first appeared in the Silurians, and passed, with the changes which have been indicated, through the Devonian and Carbonigenous

eras.

1 It must at the same time be admitted that conglomerate is, in many instances, simply a portion of the river alluvia of ancient times,-exactly resembling the gravel of

our own era.

* Literally Red Dead Liers, that is, strata of red colour, having no remains of living things in them.

F

The total number of specific forms, which had been diminishing in the carbonigenous era, is in this still further reduced; one recent author says, from about a thousand to a hundred and sixty-six, of which only eighteen are common to the inferior strata. It appears as if, while some new species continued to present themselves, the animal kingdom was now generally undergoing a decay, for even specimens of particular families are less abundant than formerly. Instead, for example, of the hundred species of corals of the carboniferous formation, there were now only fifteen, and of these but three or four abundant. Of the numerous crinoidea of the past, but one now remained, and this is rarely found. The trilobite has now vanished, to appear no more. For hundreds of brachiopods, there were now only thirty, ten of them old. The cephalopods almost disappear at the very commencement of the Permian era.

It cannot at present be determined whether this diminution of fossils is owing to an actual reduction of the amount of life in the ancient seas, or only to some such simple cause as the occurrence of deposits which were not favourable to the preservation of animal remains. It may even be that the principal cemeteries of the age have not yet been hit upon by research; for certainly this is neither the most extensively nor the most rigidly examined of the various formations, and we are made the more suspicious by finding that, at this part of the rock series, several important fossiliferous strata are present in one region and not in others. It has been ascertained, however, by Permian researches, that extensive changes of specific forms in the ancient seas were not, as has been supposed, necessarily and essentially connected with great physical disturbances; for both do we find that the unconformability of strata or memorials of disturbance between the carboniferous and Permian do not affect the fossils, and that a conformable succession of strata over the Permian is attended by a great-usually called a complete

1 Murchison's Geology of Russia in Europe.

change of species. At this termination of the Permian, it has become customary to close what is called the Paleozoic Period, or period of the most ancient forms of animal existence, on a presumption that a completely new set now enter upon the field. There seem, however, to be considerable reasons for doubting if any such decided change takes place at this point of time. Plants identical with species of the carboniferous formation are found in later formations (Trias of France and certain Liassic beds in the Alps). We have also seen that reptiles of a family hitherto supposed to commence in these superior formations are now discovered in the carboniferous beds. In that regular advance of life from inferior to superior classes there is here no interruption. Taking all things together, it seems the more reasonable supposition, that, notwithstanding conformableness of strata, a local suspension of deposits for a considerable time is indicated a time during which the usual changes of species were proceeding, probably at their usual rate-and which was sufficient to present something like a complete change of forms when the deposits were re-commenced.'

In the Permian formation, besides the principal orders of animals which previously existed, there occur undoubted remains

'Murchison's Russia; also Mr. Horner's address as president of the Geological Society, Feb. 1846.

Russia presents another notable example of a change of fossils in a comformable series of strata; that is, a series showing no record of volcanic disturbances. This takes place between the Devonian and Carboniferous formations. "The uppermost beds of the Devonian," says Sir R. Murchison, "loaded with Holoptychius and Onchus, Coccosteus, Placosteus, and Dendrodus, are at once conformably surmounted by strata containing the most universally diffused carboniferous types. In short, fishes identical with those of the Old Red Sandstone of Scotland are invariably surmounted by the Stigmaria ficoides and the large Producti of our British mountain limestone; and thus the examination of Russia has taught us, not only in this instance, but also in the overlying Permian succession, that the great changes in animal life have not been dependent on physical revolutions of the surface, but are distinct creations, independent of any proximate local causes; though I would by no means pretend to say that the grand operations of change which have affected the conterminous regions of Russia did not tend to produce these results."

of the reptilian class. As yet, only a few such bones have been discovered in Zechstein of Thuringia in Upper Saxony, and in quarries near Bristol. By Professor Owen, who has carefully examined them, they are said to be of the lacertilian or lizard order (specifically called by him palæosaurs, thecodonts, monitors, etc.), but for the most part of gigantic size, and differing from modern lizards in very remarkable characters of the vertebræ, teeth, and dermal plates. To them, as to all the reptiles of this

A, Oblique view of the Vertebra of a Cod; B, Section of three connected
vertebræ, showing the intervertebral spaces.

and several subsequent great periods, belonged a fish-like form of the vertebral column, in as far as its component bones were biconcave, or shaped like a double egg-cup, a peculiarity regarded by this eminent anatomist as probably fitting the animal for partially marine habits. And that the full importance of this peculiarity of the early reptiles may be appreciated, the reader must be made aware that modern reptiles have a ball-and-socket form of the vertebræ that is, a convexity at the one side fitting into the hollow of the adjacent bone; but this form only when they are mature animals, for in the embryotic state of the crocodile