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GEOLOGICAL PHENOMENA OF AUVERGNE.-Wall-case G.-The fossils in this cabinet are chiefly remains of extinct mammalia from tertiary lacustrine marls and limestones, and were collected by M. Pomel, an eminent French naturalist, from a province in Central France, named the Limagne d'Auvergne ; a district of surpassing interest in a geological point of view, for it presents the remarkable phenomenon of an extensive tract of country which has been subjected through long periods to successive volcanic eruptions, and yet the area of those physical revolutions, though studded with extinct craters, and traversed by lava currents, still preserves its ancient geographical features.

The specimens are at present unarranged; and many of the bones, teeth, crania, and jaws, are not entirely cleared from the rock; but the eminent zoologist, MR. WATERHOUSE, of the paleontological department of the British Museum, has already with great skill and patience brought to light many unexpected treasures in the collection purchased of M. Pomel by the Trustees, and is diligently engaged in


developing and determining the zoological characters and relations of this highly interesting series of mammalian remains.

The country whence these fossils were obtained, and which is the site of the extinct volcanoes, is about 220 miles south of Paris, and forms a vast plain, situated in the department of the Limagne d'Auvergne. It is so remarkable for its fertility, that it is called the Garden of France; a quality attributable to the detritus of volcanic rocks which enters into the composition of the soil. It is enclosed on the east and west by two parallel ranges of gneiss and granite. Its average breadth is twenty miles, its length between forty and fifty, and its altitude about 1,200 feet above the level of the sea. The immediate subsoil of this plain is formed of alluvial deposits composed of granitic and basaltic pebbles and boulders, spread over beds of freshwater limestone.

Hills of various elevations are scattered over the plain; and the river Allier flows through the district over strata of limestone, marl, and sandstone, except where it has excavated a channel through these sedimentary beds to the foundation rock of granite. The calcareous deposits are the remains of a formation which once constituted an ancient plain of a higher elevation than the present tract; many of these hills are capped by a crest of basalt, to which their preservation is in great measure owing; others have escaped destruction in consequence of the durable and hard nature of the limestone of which they are composed.

Thus we have as the ground plan of the district, an extensive plain, checquered with low hills of fresh-water limestone, that are capped with compact lava;' the boundaries of this tract being a range of primary rocks, 3,000 feet high. To the westward the limestone disappears, and a plateau of granite rises to a height of 1,600 feet above the valley of Clermont, being 3,000 feet above the level of the sea. This elevated tract supports a chain of volcanic cones and dome-shaped mountains," about seventy in number, which vary in altitude from 100 to 500 feet above their bases, and form an irregular range of

1 I would refer the reader to "Wonders of Geology," p. 268, for a more particular account of these phenomena; the classical works on the geology of Auvergne are therein pointed out.

2 Ibid. Pl. II.

nearly twenty miles in length, and two in breadth. The highest point of this chain is the Puy de Dome, which is 4,000 feet above the level of the sea, and is entirely composed of volcanic matter; it has a regular crater which is 300 feet deep, and nearly 1,000 feet in circumference.

The volcanic vents of Central France are of very different ages; some being of immense antiquity, whilst others are evidently of comparatively recent origin, for they have exploded through ancient beds of basalt: but even the most modern of the craters and lava streams, belong to a period very remote in relation to the present condition of the country.

In the plains, and on the flanks of the volcanic mountains, and rising into hills of moderate elevation, are a series of fresh-water strata, with alternations of scoriæ, basalt, &c. based on the foundation rocks of granite and gneiss. The lowermost beds are for the most part composed of clay, sand, and breccia, without organic remains. The next in order are fresh-water tertiary limestones and calcareous marls, in nearly horizontal strata, amounting in total thickness to 900 feet. It is in these beds that the mammalian remains we have to notice occur: they are associated with lacustrine and fluviatile shells, as potamides, planorbis, helix, limnea, &c. and terrestrial plants. In some localities there are beds of gypseous and laminated marls, and intercalations of siliceous limestones; in other areas, the limestone has an intermixture of volcanic matter, and presents the characters of a sediment tranquilly deposited in a lake, into which ashes and scoria were showered from a neighbouring volcano.

The fresh-water limestones are in many places covered by thick beds of basalt and scoriæ, and the summits of the lower hills composed of these strata are capped by basaltic lava. The Drift, or alluvial sand and gravel, contains bones of mastodons, elephants, hippopotami, &c. as in other countries of Europe; and the more modern superficial soil abounds in remains of dogs, hares, beavers, bears, &c.

EOCENE AND MIOCENE MAMMALIA. The mammalian remains from this region have been referred to three very distinct geological epochs;1 viz. :

1 See Sir Charles Lyell,-" Proceedings of the Geol. Society," 1845,

I. Mammalia of the most ancient fresh-water strata; from the presence of remains of palæotheria, anoplotheria, and other Cuvierian pachyderms, these deposits are regarded as Eocene and Miocene tertiary.

II. Mastodon, Hippopotamus, Elephant, Horse, Tapir, &c. all supposed to be extinct species; the beds in which these occur are separated from the previous group by ancient lavas.

III. Bones from the sandy marl and alluvial debris. These are referable to small Rodents (Lagomys), and nearly 50 species of other existing mammalia; as Squirrel, Hare, Martin, Dog, Cat, &c. Hog, Ox, Deer, Horse; and Reptiles, as Frogs, Lizards, Snakes; several kinds of Birds; and eggs of reptiles and birds.1

DISCOVERIES OF M. POMEL.-Sir Charles Lyell, in the recent edition of his " Elements of Geology," remarks, that it cannot with certainty be determined whether all the fresh-water strata of the Limagne d'Auvergne belong to one period, because extensive beds both of the arenaceous and marly groups are often devoid of fossils. "Much light has been thrown on the mammalian fauna by the labours of MM. Bravard and Croizet, and by those of M. Pomel. The last-mentioned naturalist has pointed out the specific distinction of all, or nearly all, the mammalia, from those of the tertiary gypseous series near Paris. Nevertheless, many of the forms are analogous to those of eocene quadrupeds. The Cainotherium, for example, is not far removed from Anoplotherium, and is, according to Mr. Waterhouse, the same as the genus Microtherium of the German naturalists. There are two species of marsupial animals allied to Didelphys, a genus also found in the Paris gypsum. The Amphitragulus elegans of Pomel, has been identified with a Rhenish species from Weissenau near Mayence, called by M. Kaup Dorcatherium nanum; and other Auvergne fossils, e. g. Microtherium Reuggeri, and a small rodent, Titanomys, are specifically the same with mammalia of the Mayence basin."2

COLLECTION IN Wall-case G. -The collection formed by M. Pomel, which is now before us, is chiefly, as I am informed

1 "Wonders of Geology," p. 274.

2 "Manual of Elementary Geology," 1851, p. 188. See also p. 425, of the same volume.

by Mr. Waterhouse, from the eocene marls and limestones, near Clermont; fresh-water shells are associated with the bones, and no traces of marine remains of any kind have been discovered.

The bones and teeth, though friable, are in a beautiful state of preservation; and Mr. Waterhouse has most successfully developed some exquisite crania and jaws of an extraordinary little extinct Pachyderm (not larger than a rabbit) which inhabited ancient Auvergne.

There are bones and teeth of many genera of Anoplotheridæ.

Anthracotherium, several species.

Cainotherium a sub-family of Anoplotherida.

A small and very peculiar Ruminant.

An animal approaching the Musk-deer (Amphitragalus of M. Pomel).

Hyænodon (found, also, at Hordwell, in Hants).'

Many small Rodents of species and genera discovered by Searles Wood, Esq., in the eocene deposits, at Hordwell, in Hants.2

Small carnivora, allied to the Weasels. (Mustelidæ.)
Jaws of small marsupials. (Didelphida.)

Fresh-water Turtles. (Emydians.)

Crocodilian and batrachian reptiles.
Small lacertian reptiles.

Birds several species and genera.

Eggs of birds, and probably, also of reptiles.

For the above list of this highly interesting series of mammalian remains from the tertiary lacustrine deposits of the volcanic regions of France, I am indebted to the kindness of Mr. Waterhouse; when this collection is thoroughly arranged, and the characters of the species and genera are determined, it is to be hoped this accomplished naturalist will lay before the public a full account of these palæontological treasures.

TROGONTHERIUM CUVIERI. -Wall-case G.-The rivers of England and of the Continent were inhabited by Beavers at no very remote period, and in more ancient times extinct species or sub-genera of this family, of a large size, were denizens of modern Europe. In the lowermost compartment of

1 See my "Geology of the Isle of Wight," p. 438.

2 Figured and described in " London Palæontological Journal," Pl. II.

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