The fish of Monte Bolca, and of Italy in general, in deed, must, on the contrary, be considered as of marine origin. They are found in a manly slate, which is part of the extensive formation, called by Brocchi Subappenine, and which covers so large a part of Italy. It is the gene ral character of this tract, wherever it occurs, to consist of two beds, the one of sandstone and sand, and the other of marl and similar matters beneath it. In both of these, but most abundantly in the lowest, there are found nu merous marine remains, principally shells, extremely well preserved, and often, indeed, with the ligament yet entire, together with fishes, and, among the rest, entire skeletons of whales and dolphins ; oyster shells sometimes adhering to the former, and proving, together with their great in tegrity, that they have not undergone transportation. Such is the general character of this deposit, and Monte Bolca forms a part of it. In this hill, however, the fish do not lie in continuous strata, but in distinct and detached masses among the looser matters. Upwards of an hundred spe cies are said to have been ascertained; some of them be ing inhabitants of the present Mediterranean, others being as yet unknown, and some, as it is imagined, being now found in the Indian and other distant seas. M. Blainville's criticisms have considerably reduced this number, and we ourselves doubt if there are fifty distinct species.
The forms of these fishes are well defined, and this is particularly the case with the harder parts. The animal matter is indurated, and mixed with the including earth ; is of a brown colour, and is so thick as to project from the stone, so as to admit of being separated. This part is brittle and glossy, but the bones are sometimes converted into calcareous spar. From this perfect state of preserva tion, there can be no doubt that the operation by which these fishes were thus inclosed was sudden, and that the whole stratum, at first so soft as to entangle them, was dried within a very short time, without which the softer parts must have been decomposed. The other pheno mena already mentioned respecting the Subappenine for mation, and other circumstances relating to the state of Italy and to the operations of volcanos elsewhere, give us reason to think that the whole of that land has been sud denly elevated from the bottom of the sea by volcanic force, and thus the speedy consolidation and perfect pre servation of these fossils is accounted for.
In our own country, fish, or their impressions rather, have been found in the Portland stone, in the clay of Shep pey, in the Leicestershire coal, in some other limestones, and in slate. From the nature of these strata, we must consider that those found in the coal strata are of fresh water origin, in all probability, while the others are ma rine. We have also reason to think that they are all lost species. But, with respect to those of Italy, it is not only certain that many are still existing in the surrounding seas, but there is every reason for supposing that such should be the case. We cannot here admit that any of the specimens of Monte Bolca have been brought from intertropical seas, as some have thought fit to imagine; as their condition precludes all possibility of transporta tion; while there is no more reason to wonder why they do not all now exist in the Mediterranean, than that we do not find the whale and dolphin there, or that this land and the adjoining countries of Germany and France are not now inhabited by the different kinds of lost terrestrial ani mals that are found so abundantly in the upper alluvia As M. Blainville has recently bestowed much trouble
on this subject, and has attempted to arrange some of the fossil fishes in the present genera, while he has formed new ones for those which could not be so distributed, we shall here give a condensed view of his catalogue ; distinguish ing also the places in which they are found.
The fishes, or Ichthyolites, of Glaris in Switzerland, are found in a small valley to the south-east of this place in a greywacke schist, which contains mica, and is interstrati fied with limestone. These remains are always imperfect, and little more than impressions of the skeletons, either entire or in fragments. No fossil shells are found among them ; and although Haller has said that he observed the impressions of ferns in the same place, M. Blainville does not choose to believe that, because Brongniart could not discover any. In an abstract view, we consider this sort of negative evidence as of no value; and should certainly feel no inclination to reject the testimony of Haller in fa vour of that of Brongniart. We have other reasons for doubting the validity of M. Blainville's conclusions on every subject in which a geological question is concerned, what ever we may think of his zoological arrangements ; and we are sorry to add, that we feel ourselves compelled to adopt the same hesitation with respect to many other names, who, however expert in comparative anatomy, or acquainted with these departments of natural history, have decided on geological facts in defiance of all evidence, or with an utter ignorance of that subject. With respect to the strata of Glaris, we entertain no doubt that they belong to a fresh-water formation, and that Haller is right; and that M. Blainville's fishes also are fresh-water, and not ma rine animals.
This confounding of marine and terrestrial fishes is a matter of no small moment, if the question of the former presence of the sea in any particular spot is to be decided by it ; and, little as we are inclined to trust to the geolo gical acuteness of such observers in similar cases, we are fully as little willing to believe that a zoologist can, from a few imperfect impressions and bones, decide whether a fish belonged to the sea or to interior lakes ; and we feel no hesitation in adding, not often even on its genus. We mean no exclusive disrespect towards this author ; but, we observe, that a rage has lately sprung up for arrangements and determinations of fossil species and genera, from a species of evidence that is absolutely incapable of deter mining questions of such intricacy. Every man must not imagine himself a Cuvier.
We therefore feel very indifferent, whether these ob servers agree that the strata of Glaris are transition or secondary ; being pretty well convinced that their deter minations areas much conjectural as aught else ; and shall therefore enumerate the Ichthyolites in question ; taking the ancient and new genera and species as we find them, without, nevertheless, being always convinced that any one of them is truly named or understood.