Bones found

in tufo.

and of some other parts of Auvergne, where fine lentils of chalcedony, and chalcedonic crystallised quartz, are found. The perlstein of Sancta Fiora, on the confines of Tuscany, is an analogous chalcedonic substance, which is also found in a tufo; and the muller-glass, which was discovered by Dr. Muller of Frankfort, and thought. to be a glass, is only a very fine chalcedonic substance, with the lustre and transparence of glass.

Muller observed this substance formed in drops on a porous lava*. I have found it on the tufos of Bocheneim, near Frankfort, spread like a shining varnish, and pretty thick, on the surface.

"Of some substances of the organised kingdom, which are accidentally found in tufos.

"1. The fossil tusks of the elephant have been found in tufo in the neighbourhood of Rome. The Duke of Rochefoucault found one himself of a gigantic size, as it was eight feet long and fourteen inches in circumference: he

*Faujas has added, Geol. ii. 147, that Muller said to him, "I have infinite obligations to natural history, it charms my last moments, and the weight of ninety-five years, my present age, does not weaken its power. One has always fresh enjoyments, one lives without reproach, and one does not die, but falls asleep."

sent it to M. Buffon: it may be seen in one of the galleries of the Museum of Natural History at Paris.

"2. The grinders and the thigh-bones of an elephant, were discovered in the midst of tufo, in a vineyard not far from the Porta del Popolo at Rome. Count Morozo sent the description of it to M. de Lacepede, who inserted it in the Journal de Physique, vol. 54, page 444.

"3. In digging some years since, in a tufo of Mont Couerou, in the department of Ardèche, near the commune of Arbres, to find a spring, M. Lavalette found a tusk of a young elephant, half petrified, but perfectly characterised. On this subject I published an account in the Annals de Museum, see vol. ii. p. 23, where the tusk is represented.

"4. Different kinds of shells are found, as well univalve as bivalve, in some tufos; and these shells are scarcely altered.

"The valley of Ronca, so well described by Fortis, and which he justly calls volcanico-marine, in the territory of Verona, contains many shells in the tufo.

"Dr. Thompson an English naturalist, residing at Naples, possesses in his rich collection some fine samples of tufos, which are found scattered in different places of Vesuvius. Some con

Shells.

Lignite.

Plants.

tain marine substances, and he has one in which is distinguished a madrepore, common in the sea of Naples; it is the retepora spongites of Linneus, the porus anguinus of Imperati.

"In the magnificent gardens of the Elector of Hesse Cassel,, at Waissenstein, in the midst of a volcanic soil, is found a sandy tufo, filled with beautiful shells of different kinds; among which I observed the Venus islandica of Lamarck, and the arca pilosa of Linneus.

"I possess in my collection, a shell of the genus cone, in a very hard volcanic tufo, which has filled its interior, found on the sea shore at St. Croix, in Teneriffe; it was given to me by M. Bailly, one of the mineralogists in the expedition of Capt. Baudin.

"5. I have already mentioned wood changed to coal, which is found at a great depth in the tufo, of the environs of Andernach, and in that of Lipara.

" 6. I ought not to pass in silence, the tufo of Rochesauve, in Vivarais, of which the beds seem to alternate with other fossile beds of a light marl, which contains leaves of trees and plants, whose fibres are in the most beautiful preservation, but whose parenchyme is black and carbonised. I have a numerous collection I of those plants, which I gathered on the spot:

intend shortly to make them public, by having them engraved, and to give the explanations of those which have relations with known species."

HYPONOME I. VOLCANIC BRICIA.

The various kinds are already mentioned.

Micronome 1. Peperino.

From the environs of Vesuvius, &c.*

Micronome 2. Leucite Lava.

From Vesuvius, Albano, &c.

NOME IX. SUBSTANCES EJECTED OR
CHANGED.

Many kinds of rocks are at various periods ejected by volcanoes; often with some marks of fusion, but in many instances, exploded by the vapours, without being visibly affected by heat. Whole masses of rock, nay mountains, are also found changed by the action of the subterranean vapours, as the celebrated Puy-de-Dome, which, Puy-de-Dome. according to Saussure § 728, 729, is a porphyry with a base of earthy felspar; and he found one of the same kind in the Valorsine. Mont Dor

• Monte Nuovo near Naples, consists of indurated powder, pumice, and fragments of lava intermingled, forming a peperino.

also presents granite, evidently affected by heat, the felspar having become dull and shattered*. Several altered rocks are found in volcanic regions; and even the lavas sometimes become white, by the action of sulphuric vapourst.

Parasitic stones.

HYPONOME 1. LIMESTONE.

This substance deserves the first place, as that ejected by Vesuvius is not only more frequent in cabinets than any other exploded rock, but contains several remarkable parasitic stones; such as 1. The Vesuvian of Werner, and idocrase of Hauy, the jacint of Vesuvius according to Saussure, the colour resembling that of a pale jacint It is also found of an olive green, whence it is sometimes called chrysolite by the Neapolitan lapidaries. It would seem that the latter is, however, the same with the olivine of Werner, also called volcanic chrysolite. 2. The sommite of

* It is surprising that the French writers continue to spell d'Or as if it were the golden mountain, while Le Grand (Voyage d'Auvergne ii. 66.) has demonstrated, that the name was taken from the river Dor, which, with the Dogne, forms the Dordogne.

↑ The lava decomposes into clay, or rather the argil displays itself; whence the environs of volcanos are very fertile.

Because the olivine is found in basalt, the Wernerians reject it from the volcanic substances, while it is in fact the common volcanic chrysolite, as Breislak has shewn. Gioeni, p. 217, observes, that many scoriæ of Vesuvius and Etna contain a yellowish substance like glass, perfectly resembling that in the native iron of Siberia.