On the opposite page an ideal landscape of the period is represented (Plate XXL), in which the Iguanodon and Megalosaurus struggle for the mastery in the centre of a forest, w^iich enables us also to convey some idea of the vegetation of the period. Here we note a vegetation at once exotic and temperate — a flora like that of the tropics, and also resembling our own. On the left we observe a group of trees, which resemble the dicotyledonous plants of our forests. The elegant Credneria is there, whose botanical place is still doubtful, for its fruit has not been found, although it is believed to have belonged to plants with two seed-leaves, or dicotyledonous, and the arborescent Amentacece. An entire group of trees, composed of Ferns and Zamites, are in the background; in the extreme distance are some Palms. We also recognise in the picture the alder, the wych-elm, the maple, and the walnut-tree, or at least species analogous to these.

The Neocomian beds in France are found in Champagne, in the departments of the Aube, the Yonne, the Haute-Alps, &:c. They are largely developed in Switzerland at Neufchatel, and in Germany. 1. The Lower Neocomian consists of marls and greyish clay, alternating with thin beds of grey limestone. It is very thick, and occurs at Neufchatel and in the Drome. The fossils are Spaiajigus retiisus, Crioceras (Fig. 125), ADWionites Asta'iaims^ &c. 2. Org07iian (the limestone of Orgon). This group exists, also, at Aix-les-Bains in Savoy, at Grenoble, and generally in the thick, white, calcareous beds which form the precipices of the Urome. The fossils Chai7ia avimojiia^ Pigaidus^ &c. 3. The Aptim (or Greensand) consists generally of marls and clay. In France it is found in the department of Vaucluse, at Apt (whence the name Aptien), in the department of the Yonne, and in the Haute- Marne. Fossils, Ancyloceras Matheroniaiius^ Ostrea aquila.

and PlicaUila placunea. These beds consist here of greyish clay, which is used for making tiles; there of bluish argillaceous limestone, in black or brownish flags. In the Isle of Wight it becomes a fine sandstone, greyish and slightly argillaceous, which at Havre, and in some parts of the country of Bray, become well-developed ferruginous sandstones.

We have noted that the Lower Neocomian formation, although a marine deposit, is in some respects the equivalent of the Weald Clay^ a fresh-water formation of considerable importance on account of its fossils. We have seen that it was either formed at the mouth of a great river, or the river was sufficiently powerful for the fresh-water current to be carried out to sea, carrying with it some animals, forming a fluviatile, or lacustrine fauna, on a small scale. These

Fig. 143. — Cypris spinigcra. Fig. 144.— Cypris Valdensis

were small Crustaceans of the genus Cypris, with some molluscous Gasteropoda of the genera Mdajiia, Paludina, and acephalous MoUusca of the five genera Cyrena, Unio, Mytihis, Cydas, and Ostj'ca. Of these, Cypris spinigera {¥%. 143) and Cypris Valdensis (Fig. 144) may be considered as among the most characteristic fossils of this local fauna. The Cretaceous series is not interesting for its fossils alone; it presents also an interesting subject for study in a mineralogical point of view. The white Chalk, examined under the microscope by Efirenberg, shows a curious globiform structure. The green part of its sandstone and limestone constitutes very singular compounds. According to the result of Berthier's analysis, we must consider them as silicates of iron. The iron shows itself here not in beds, as in the Jurassic rocks, but in masses, in a species of pocket in the Orgonian beds. They are usually hydrates in the state of hematites, accompanied by quantities of ochre so abundant that they are frequently unworkable. In the south of France these veins were

ORGONIAN BEDS. 299 mined to a great depth by the ancient monks, who were the metallurgists of their age. But for the artist the important Orgonian beds possess a special interest; their admirable vertical fractures, their erect perpendicular peaks, each surpassing the other in boldness, form his finest studies. In the Var, the defiles of Vésubia, of the Esteron, and Tinéa, are jammed up between walls of peaks, for many hundreds of yards, between which there is scarcely room for a narrow road by the side of the roaring torrent. “In the Drôme,” says Fournet, “the entrance to the beautiful valley of the Vercors is closed during a part of the year, because, in order to enter, it is necessary to cross the two gullies, the Great and Little Goulet, through which the waters escape from the valley. Even during the dry season, he who would enter the gorge must take a foot-bath.

“This state of things could not last; and in 1848 it was curious to see miners suspended on the sides of one of these lateral precipices, some 450 feet above the torrent, and about an equal distance below the summit of the Chalk. There they began to excavate cavities or niches in the face of the rock, all placed on the same level, and successively enlarged. These were united together in such a manner as to form a road practicable for carriages; now through a gallery, now covered by a corbelling, to look over which affords a succession of surprises to the traveller.

“This is not all,” adds M. Fournet: “he who traverses the high plateaux of the country finds at every step deep diggings in the soil, designated pits or scialets, the oldest of which have their sides clothed with a curious vegetation, in which the Aucolin predominates; shelter is found in these pits from the cutting winds which rage so furiously in these elevated regions. Others form a kind of cavern, in which a temperature obtains sufficient to freeze water even in the middle of summer. These cavities form natural glaciers, which we again find upon some of the table-lands of the Jura.

“The cracks and crevasses of the limestone receive the waters produced by falling rain and melted snow; true to the laws of all fluid bodies, they filter through the rocks until they reach the lower and impervious marly beds, where they form sheets of water, which in course of time find some outlet through which they discharge themselves. In this manner subterranean galleries, sometimes of great extent, are formed, in which are assembled all the marvels which crumbling stalactites, stalagmites, placid lakes, and headlong torrents can produce; finally, these waters, forcing their way through the external orifices, give rise to those fine cascades which, with the first gushing torrent, form an actual river.”

The Allien of Ale. D'Orbigny, whieh Lyell considers to be the equivalent of the Gault^ French authors treat as the ^^ glauconie'' formation, the name being drawn from a rock composed of chalk with greenish grains of glaucotiite, or silicate of iron, Which is often mixed with the limestone of this formation. The fossils by which it is identified are very varied. Among its numerous types, we find Crustaceans belonging to the genera Arcania and Corystes; many new Mollusca, Biicci7ium^ Sokn, Fterodonta, Volufa, C/iama, Sic.; great numbers of molluscous Brachiopods, forming highly-developed submarine strata; some Echinoderms, unknown up to this period, and especially a great number of Zoophytes; some Foraminifera, and many Polyzoa (Bryozoa). The glauconitic formation consists of two groups of strata: the GmiU Clay and the g/aucomtic chalk, or Upper Greensand and Chloritic Marl.

Upper Cretaceous Period.

During this phase of the terrestrial evolutions, the continents, to judge from the fossilised wood which we meet with in the rocks which now represent it, would be covered with a very rich vegetation, nearly identical, indeed, with that which we have described in the preceding sub-period; according to Adolphe Brongniart, the " age of angiosperms" had fairly set in; the Cretaceous flora displays, he considers, a transitional character from the Secondary to the Tertiary vegetation; that the line between the gymnosperms, or naked-seeded plants, and the angiosperms, having their seeds enclosed in seed-vessels, runs between the Upper and Lower Cretaceous formations. " We can now affirm," says Lyell, " that these Aix-la-Chapelle plants, called Credneria, flourished before the rich reptilian fauna of the secondary rocks had ceased to exist. The Ichthyosaurus, Pterodactyle, and Mosasaurus were of coeval date with the oak, the walnut, and the fig."'"' The terrestrial fauna, consisting of some new Reptiles haunting the banks of rivers, and Birds of the genus Snipe, have certainly only reached us in small numbers. The remains of the marine fauna are, on the contrary, sufficiently numerous and well preserved to give us a great idea of its riches, and to enable us to assign to it a characteristic facies. The sea of the Upper Cretaceous period bristled with numerous sub-marine reefs, occupying a vast extent of its bed — reefs formed of

• Ly ell's "Elements of Geology," p. 333.

UPPER CRETACEOUS PERIOD, 3OI

Rudistes (Lamarck), and of immense quantities of various kinds of corals which are everywhere associated with them. The Polyps, in short, attain here one of the principal epochs of their existence, and present a remarkable development of forms; the same occurs with the Polyzoa (Bryozoa) and Amorphozoa; while, on the contrary, the reign of the Cephalopods seems to end. Beautiful types of these ancient reefs have been revealed to us, and we discover that they have been formed under the influence of submarine currents, which accumulated masses of these animals at certain points. Nothing is more curious than this assemblage of Rudistes —still standing erect, isolated or in groups — as may be seen, for instance, at the summit of the mountains of the Comes in the Corbieres, upon the banks of the pond of Berre in Provence, and in the environs of Martigues, at La Cadiere, at Figuieres, and particularly above Beausset, near Toulon.

" It seems," says Alcide D'Orbigny, " as if the sea had retired in order to show us, still intact, the submarine fauna of this period, such as it was when in life. There are here enormous groups of Hippurites in their places, surrounded by Polyps, Echinoderms, and Molluscs, which lived in union in these animal colonies, analogous to those which still exist in the coral-reefs of the Antilles and Oceania. In order that these groups should have been preserved intact, they must first have been covered suddenly by sediment, which, being removed by the action of the atmosphere, reveals to us, in their most secret details, this Nature of the past."

In the Jurassic period we have already met with these isles or reefs farmed by the accumulation of Coral and other Zoophytes; they even constituted, at that period, an entire formation called the Coral-rag. The same phenomenon, reproduced in the Cretaceous seas, gave rise to similar calcareous formations. We need not repeat what we have said already on this subject when describing the Jurassic period. The coral or madrepore isles of the Jurassic epoch and the reefs of Rudistes and Hippurites of the Cretaceous period have the same origin, and the atolls of Oceania are reproductions in our own day of precisely similar phenomena.

The invertebrate animals which characterise the Cretaceous age are among.

Cephalopoda.

Nautilus sublcevigatus and N, Danicus; Ammonites rostratus; Belemni' tella mucronata.

Gasteropoda.

Vobita elongata; Phortis canalicidatus; Nerinea hisulcata; Pleurotomaria Fleuriausa, and P. Santoneiisis; Natica^ supracreiacea.

ACEPHALA.

Trigonia scabra; Itiocemijfiis problematicus 2C£iA I. Lmnarckii; Clavi-gella cretacea; Pholadoinya ceqiiivalvis; Spondylus spinosus; Ostrea vesicidaris; Ostrea larva; Jaiiira quadricostata; Area Gravesii;

Hippiirites Toueasiajius and H. organisans; Caprina Agidlloni;

Radiolites radiosus^ and R. acuticostus.

Brachiopoda.

Crania Ignabergensis; Terchratida obesa.

POLYZOA (BrYOZOA) AND ECHINODERMATA.

Reticidipora obliqua; Anafiehyfes ovatus; Micr aster

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