that the marsh land which extended from Ravenna to Aquileia, or rather, as some think, to Altino, was covered with salt water; whereas many may be brought forward to show, that the greater part of it has been overflowed by rivers. The Po, above all the rest, contributed to inundate a great tract of it; and attempts were made, at a very early period, even in the time of the Etrurians, to recover the land that had been encroached upon by its waters, by cutting several canals near its mouth, in order that it might discharge itself more quickly into the sea. Of the seven mouths of this river, two only belong to it naturally, as Cellarius has satisfactorily shown: all the rest are artificial cuts. p. 112.

There are, however, undoubted proofs of the Adriatic having, in some situations, extended further inland than it does at present. Adria, Ravenna, and Spina were at one time sea-ports: but the first of these places is now about twenty miles inland; the second about four miles; and Spina, which was built at the mouth of one of the branches of the Po, was, at the beginning of the Christian era, eleven miles from the sea-coast.⚫ Mesola was built close to the sea in 1581 by Alphonso II. Duke of Ferrara; in 1599 its eastern wall was already two-thirds of a mile distant from it; and, in 1750, it stood from six to seven miles inland.

But, on the other hand, Brodolo stood in the same situation seventeen centuries ago that it does now; for Pliny speaks of it as a port of the Laguna, where some rivers emptied themselves into the sea: the same may be said of Chioggia, Fossa Clodia, which was then a port at the mouth of the Brenta and Bacchiglione. Altino, built like Ravenna, in the midst of salt marshes, is still (or rather the place where it stood) washed by the Laguna di Cona, at least in high tides. Padua, in the time of Livy, was seventeen miles from the shore, as it is now. Dolomieu, on the authority of Strabo, has said, that about the beginning of the Christian era, an arm of the sea reached the walls of that city: But he must have misunderstood that author; for Strabo, so far from asserting that the Adriatic extended to Padua, says, that, to reach the sea. they sailed down the Brenta, then called the Meduacus, which discharged itself into the sea at the great port of the same name, and which is now called Malamocco. To this may it be added, that the description given by Livy himself (which is the most ancient document that can be brought forward) of the state of the Laguna, and of the appearance of the country around Padua, perfectly applies at the present day. "Penitus ad littora Venetorum pervenit: ibi expositis paucis, qui loca explorarent, quum audisset, tenue prætentum littus esse; quod transgressis stagna ab tergo sint, irrigua æstibus maritimis; agros haud procul proximos campestres cerni; ulteriora colles." This shore, as all critics agree, was that of Malamocco, which appears exactly like a narrow strip of land: The salt marshes were the Lagune; the fields, those between Chioggia and Fusina; and the hills, the Euganean

Hills.'

M. Brocchi might have added the continuation of the passage he has quoted; for it proves still more distinctly the error of Dolomica. Inde esse ostium fluminis præalti, quo circumagi naves in stationem tutam vidisse: (Meduacus amnis erat) eo invectam classem subire flumine adverso jussit. Gravissimas navium non pertulit alveus fluminis: in leviora navigia transgressa. multitudo armatorum ad frequentes agros, tribus maritimis Patavinorum vicis colentibus eam oram, pervenit. Lib. X. 2.and there are some further illustrations in the same chapter.

There does not appear to be any essential or constant difference of species in the fossil shells found in the Sub-Apennine Hills, either in regard to the greater or less depth of the strata in which they are found, or the materials of which the strata are composed. They are not scattered confusedly through the different beds, but often appear to be distributed in families and distinct species: that distribution, however, has no correspondence with the situation of the beds. Not only the shells which are found in the present sea, but those of which the prototypes are unknown, the indigenous, as well as the exotic, are found both in the marl and in the sand that lies over it. There are perhaps some exceptions, some shells which belong more particularly to the sand; but they are not such as to warrant any general deduction. All the tertiary deposits do not contain shells, there being extensive tracts where they are either wholly wanting, or are only to be traced by some scattered vestiges, although the materials composing those districts are the same as those beds which contain the fossil shells in greatest abundance.

There is, in general, a great analogy between the fossil shells found in different parts of Italy. The same species are found in Piedmont, in the territories of Placentia and Bologna, in Romagna, Tuscany and Puglia, and even in Calabria, as is shown by the work of Scilla. It is also remarkable, that some particular shells, the originals of which are unknown, are common in several places far distant from each other. p. 145.

The fossil shells of the Sub-Apennines may be divided into two general classes, the one comprehending the shells that are still found in the sea, the other comprehending those whose prototypes are unknown. The first of these classes may be further subdivided, by distinguishing the species found in the Adriatic and Mediterranean from those which belong to distant seas. The number of the indigenous shells is very considerable; and there are many examples of those which have been described by naturalists as peculiar to the Asiatic, African and American seas. Among the most remarkable of these, are the Bulla Ficus

of the Indian and American Ocean, the Buccinum Plicatum of Jamaica, the Turbo Imbricatus of the Atlantic, the Murex Ramosus of the Red Sea and Persian Gulph, and the Murex Sinensis of the coast of Africa.

"That there are innumerable instances of the existence of fossil organized bodies in such situations as incontestably prove that the surface of the earth has undergone the most extraordinary changes, every geologist admits; but M. Brocchi shows, that some geologists have been rather hasty in their conclusions with respect to many of those fossil shells which were said to belong to climates far distant from that where they are found. Be fore we can decide upon the foreign origin of any fossil shell, it is obviously necessary to be well acquainted with those existing in the surrounding seas, not only along the coasts, but in the less accessible depths; and as the difficulty of acquiring this information is necessarily great, there should be a proportionate degree of caution in coming to that decision.

The Zoology of the Adriatic has been very accurately investi gated by Donati, Ginamni, Bianchi, Olivi, and Renieri. The work of Olivi, M. Brocchi considers by far the most valuable, It was published in 1792, under the title of Zoologia Adriatica, but was left unfinished by the premature death of the author.The same subject has since that time been followed up with great care by Renieri, Professor of Natural History in the University of Padua.

We learn from the work of Olivi, that many of the shells which were considered as belonging exclusively to the Asiatic and American seas, are found in the Adriatic; and Renieri has discovered twice as many species as were known to his predecessor. To be convinced with how little accuracy the habitats of many shells have been given, it is only necessary to compare the thirteenth edition of the Systême de la Nature, with the Prodromus of the work of Renieri. He has found fifty-five different species that were supposed to exist only in distant seas. Of these, twelve were said to belong to the Indian Ocean, seven to the Indian Ocean and Eastern coasts of Africa, eight to the Western coasts of Africa, six to the American shores of the Atlantic, three to the Islands of Nicobar, near the Bay of Bengal, two to the coasts of South America, one to the Caspian, five to the European Ocean, and eleven to the North Seas. Besides these, he has also found in the Adriatic, ten different species, the habitats of which were unknown to Linnæus. Similar results to these have been obtained by Poli in his examination of the sea Dear Naples.

The same correction must also be made in regard to the ha

bitats of Zoophytes, and particularly the genus Isis and the Madrepores. Not many living species of these are found in the Adriatic; but they abound in the Mediterranean, as appears from the work of Maratti, published at Rome in 1776.-Of these found in a fossil state, many different species have been found in the Mediterranean and Adriatic, which were said to belong to the Indian Ocean, the Red Sea, the West Indies, &c.

If equally accurate researches were made in the Ichthyology of our seas, I am very confident that many of those fishes would be found which are described as inhabitants of the Indian and American seas, and that we should discover the prototypes of many of those now existing in a fossil state at Monte Bolca. Of the one hundred and twenty-three species described by Volta, there are only thirtyseven belonging to the European seas, according to the classification of that author. The more our researches are multiplied, the more we shall find that the number of species of shells belonging exclusively to particular latitudes, is less considerable than is generally supposed. If it cannot be maintained that difference of climate does not affect marine organized bodies, it is certain at least that its effects are much less considerable upon them than upon the organic productions of the land, as the sea is not subject to the same changes of temperature as the atmosphere is. Although it may not be true, either, that in all places equally deep, the water is of the same temperature under every parallel, as some have asserted; it is, however, distinctly cold, even under the tropics, at very considerable depths: So that if difference of climate does materially affect some shells, it can only be those which live in shallow water, or near the coasts. p. 157-159.

In the catalogue which Lamark has given of the fossil shells that have been found in the neighbourhood of Paris, there are about five hundred species; and it is wonderful how few of them resemble those found in the Sub-Apennine Hills, and how many genera there are among them, wholly unknown in Italy. But the most remarkable difference in the fossil shells of the two countries, is in those of which the prototypes are unknown. These greatly predominate in France, and, with a few exceptions, are wholly different from those that exist in Italy. In the latter country many species are wanting which are common in the neighbourhood of Paris; and many occur in Italy that have not been found there. There are, moreover, many shells of constant occurrence in the marl, and which are now common in the Adriatic and Mediterranean Seas, that do not appear to have been met with by Lamark.

Besides these vast collections of fossil shells, the remains of many other tribes of marine animals are found in the SubApennine Hills. The most remarkable of these are the remains of great whales, not only in separate bones, but in

entire skeletons. They have been found in various parts of Tuscany, in the territory of Bologna, in Piedmont, and in the neighbourhood of Feltre, a country situated about 1200 feet above the level of the sea. Near Castell' Arquato in the territory of Placentia, a skeleton was found nearly entire, measuring 21 feet in length. All the bones were in their natural situation, and had undergone no other change than the loss of the animal gluten. Besides this skeleton, there were found a part of one still larger, and many detached vertebræ, ribs, and jawbones of the same animal. There were also found in the same neighbourhood, the skeleton of a dolphin six feet long, a part of another skeleton belonging to an animal of the same tribe, and the jawbone of a dolphin quite petrified, containing the greater part of the teeth, with their natural enamel preserved.

All these animal remains, and others of the same sort, which have been dug up in various parts of Italy, are found in the blue marl. Some of the bones found in the territory of Placentia, and the portion of the whale's jawbone found in Valdarno Inferiore, which is in the Museum of Florence, are encrusted with oyster-shells, which must have lived and grown upon them. So that it is quite evident, as M. Brocchi remarks, that these skeletons must have remained, as such, for a considerable time at the bottom of the sea, and that they cannot be considered as the remains of animals carried by some sudden inundation to the places where they were dug up.

However striking the occurrence of those bones, in such situations, may be, it is still more extraordinary to find, in the same places, the remains of those great land animals that now inhabit the torrid zone.

Among all the phenomena of Geology, there is none more wonderful than this, or one more worthy of deep reflection; nor is there any fact which is more puzzling to the ingenuity of Naturalists, who bewilder themselves in a labyrinth of conjecture, how the elephant, the rhinoceros, and the hippopotamus, should be found buried in our climates. The multitude of these skeletons renders the fact still more surprising. Targioni calculates the number of elephants' bones that had been dug up in Valdarno Superiore in his time, equal to those of twenty individuals; and this number has been so much augmented by subsequent discoveries, that the district may be considered as a vast cemetery of these gigantic animals. It was ascertained that, before the peasants of the neighbourhood thought of preserving these bones for the sake of selling them to the curious, some of them had been in the habit of surrounding their gardens with palisades of the tibia and thigh-bones of the elephant. One of the persons who are in the habit of searching for these bones, accompanied me to the hill of Poggio Rosso, where, after having

VOL. XXVI. NO. 51.

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