Near Tripoli, according to Le Brun, some ichthyolites are found, as also in different places on the coast of Bar bary, according to Shaw ; and, among the rest, at Oran. Malta and Sicily also contain some fragments, which are supposed to belong to Squali ; and it has been thought that a Cyprinus has been found in the Val di Notch There is something particularly interesting in the fossil fishes of Iceland, because their position seems to throw light on the remarkable deposit of Monte Bolca. These are found imbedded in an indurated mud or marl, of a bluish colour, and they occur at Patrik's Fiord, where it is said they are now in the act of being formed. The liv ing, or perhaps just dead fish, seems to have been first en tangled in a soft mud, which has been firmly attached to it by means of the animal matter that has mixed itself with that substance, while the harder parts, or the bones and the scales, remain unchanged. Thus the nodule that in closes them is first produced. and it remains imbedded in the surrounding materials. The Clupea sprattus has been thus found, and, as some persons think, the Salmo arcticus also.
The former are the best ascertained among the fishes in a fossil state, which appear to have belonged to sea water, with the exceptions that we formerly suggested. But there are many other ichthyolites known, which are esteemed to have had their origin in fresh water, and to be now existing in fresh-water deposits. It is plain that all these cases must be determined by a mixed kind of evi dence. The nature of the fish themselves will not ascer tain that point, unless where the absolute identity of some one species can made out. The presence of terrestrial shells is a better kind evidence ; taking it for granted that these are known, and not conjectured, to be such. But the well preserved remains of plants are the most un exceptionable of all ; while the remains of land animals are not quite so free from doubt, as we know that they are sometimes washed into the sea, and imbedded among re mains truly marine. We are fully convinced, in the mean
time, that many fresh-water formations have actually been proved ; and, from our preceding remarks on the fish of Glaris, it will be seen that we are much more inclined to extend than to contract these instances. We merely throw out these remarks, that we may not have to examine all Blainville's instances in a critical manner, and for the purpose of pointing out to our readers that there are causes for hesitation, and what the nature of the evidence supposed to establish these important points ought to be.
In what is called the " gypseous formation," and in Italy, ichthyolites are found at Scapezzano, about three miles from Sinigaglia. These are mentioned by Faujas, but without any particular description, as imbedded in an argillaceous marl between beds of gypsum. Similar spe cimens are described by the same author, and by the Abbe Fortis, as found in the promontory of Focara, in an indu rated clay, intermixed with porous lavas. They also occur near Pezzaro, in the Monte Volterrano, and in some other parts of Italy. As no descriptions of species are given, we can only remark respecting the geology of our author, that there is not the slightest evidence that these deposits belong to fresh water, and that some of them are of a dif ferent nature from others.
The geology of the French strata is better understood ; whether or not we are inclined to allow that all the ich thyolites referred to them belong to fresh-water fish.
At Aix, in Provence, these remains are lound in a gyp sum quarry ; the bed of this substance lying beneath some strata that succeed to it in the following order upwards : A bed containing the fossil in question, then a schistous and bituminous marl; a second marl, containing crystals of gypsum, and indurated calcareous marl, a whitish lime stone, and a schistose marl. These remains are chiefly the impressions of skeletons.