these general conjectures relative to the convulsions to which our sedimentary rocks have been subjected we find satisfactory proofs in the southern regions; whilst, on the contrary, in the northern, as we have already observed, the relation of arrangement between the rocks of both systems is not manifested with sufficient clearness, nor can we support the theory that the same phenomena have everywhere occurred. Having already observed that the Apennine limestone may be divided into two distinct regions, the one mountainous, the other almost level, called Murge, a fact of no slight importance appeals to our consideration, relative to the distribution of rocks of the second series in connection with this division, viz., that they only occur in the mountainous region. It was not without surprise that we traversed the province of Bari, and the neighbouring districts of the provinces of Lecce and Capitanata, seeking diligently, without success, for rocks of the second series, of which we never found a trace. We must confess that we cannot clearly account for this circumstance. Where the mountains formed of Apennine limestone rise, there must certainly have been during the epoch in which the rocks of the second series were deposited, a topographical condition completely different from the level plains. Ought this topographical difference to be considered sufficient to prescribe the limits within which such rocks can be formed? Now, as we shall presently show, among the components of these rocks, there are some which have very probably been transported from the granite mountains of Calabria, and in general consist of materials which may have come from distant places. Ought we to regard the direction in which their elements were transported as the cause of their being found in certain regions, and being wanting in others? The mineralogical composition of the fucoidal rocks is extremely varied. We may divide them into five different species, viz., limestone, marl, sandstone, limonite, and gypsum; and each of these admits of being subdivided into many varieties, of which we shall only record the principal. The varieties of most frequent occurrence in the limestone are the marly, of various colours, sometimes with those beautiful appearances which take the designs of ruined buildings (calcarea ruiniforme). Another, less frequent, but not less characteristic, is a breccia, of very
