The hills in which these caverns occur resemble each other in their composition: they are all of limestone, and all produce abundance of stalactites. These stalactites line the walls, narrow the passages, and assume a thousand various forms. The bones are nearly in the same state in all these caverns: detached, scattered, partly broken, but never rolled, and consequently not brought from a distance by water; a little lighter and less solid than recent bones, but still in their true animal nature, very little decomposed, containing much gelatine, and not at all petrified. A hardened, but still easily frangible or pulverisable earth, also containing animal parts, and sometimes blackish, forms their natural envelope. It is often impregnated and covered with a crust of stalactite. A covering of the same nature invests the bones in various places, penetrates their natural cavities, and sometimes attaches them to the walls of the cavern. This stalactite is often coloured reddish by the animal earth which is mixed with it. At other times its surface is stained black; but it is easy to see that these appearances are caused by modern occurrences, and have no immediate connection with the cause which brought the bones into these cavities. We even daily see the stalactite increasing and enveloping here and there groups of bones which it had formerly respected. This mass of earth, penetrated by animal matter, indiscriminately envelopes the bones of all the species; and, if we except some found at the surface of the ground, and which had been transported there at much later periods, which may also be distinguished by their being much less decomposed, they must all have been interred in the same manner, and by the same causes. In this mass of earth there are found, confusedly mingled with the bones (at least in the cave of Gaylenreuth), pieces of a bluish marble, of which all the corners are rounded and blunted, and which appear to have been rolled. They singularly resemble those which form part of the osseous brecciæ of _Gibraltar_ and _Dalmatia_. Lastly, what further conspires to render this phenomenon very striking, is, that the most remarkable of these bones are the same in these caverns, over an extent of more than two hundred leagues. Three-fourths and upwards belong to species of _bears_, which are now extinct. A half, or two-thirds of the remaining fourth, belong to a species of _hyena_, which is equally unknown at the present day. A smaller number belong to a species of the _tiger_ or _lion_ kind, and to another of the _wolf_ or _dog_ genus; lastly, the most diminutive have belonged to various small carnivora, as the _fox_, the _polecat_, or at least species very nearly allied to them, &c. The Kirkdale Cavern, however, forms a notable exception, inasmuch as none, or very few, bones of bears are found in it, and in its being the hyena that appears to predominate among the carnivora.