Admitting the truth of the general principle, on which these theories are founded, there are still many difficulties to be surmounted, and one of the most important lies in,the structure of Bolca. This hill is not a homogeneous mass; it consists of various sub stances, in unequal proportion, and forming four classes, according to geologists, among which are marl, spar, basalt ; coal and amber ; pyrites and hx matites ; marine plants, insects, fishes, and the re mains of terrestrial animals in a state of petrifaction. The petrified, substances do not lie in horizontal strata; horizontal so far as would result from the deposit of pulverised matter on an uneven surface ; for the masses of stone wherein they are. contained are imbedded in the sides of the hill : they seem de tached and apart from the other parts composing it, and rest in various degrees of inclination. But per haps this may be accounted for, by supposing, that subsequent to their formation, they were exposed to some violent disturbing cause, which affected their original position. There is no necessity that such disturbing cause should have approached the mra of their formation ; on the contrary, ' appearances indi cate that it has existed at a time'very remote from it. If the fishes were suddenly destroyed by some perni cious vapour, absorbed by the water where they swam, or by some lethal quality otherwise imparted to they must have remained for ages in their ori ginal state. The open mouth and distended fins ex hibited by them, naturalists have conjectured denote immediate suffocation; after which they were invol ved by the component matter of the stones contain: ing them, and themselves converted to stone. But that the deposit was made on a surface at rest, is evinced by the laminar structure of all the strata ; their whole leaves are parallel to each other, and per. fectly flat ; where their continuity is interrupted, the extremities are sharp and cleanly cut off, as if by frac ture in their horizontal position. Though the time requisite, for complete petrifaction is unknown, we may presume that it is slowly accomplished ; and if we are to credit the correctness of an observation, that in 1500 years wood was not affected above a quarter of an inch in depth, the period must almost exceed the bounds of calculation. Therefore it is not unlikely that two great epochs are to be counted in the formation of Mount Bolca and its singular fossils : first, that which occasioned the sudden de struction of an infinity of living beings, and their un disturbed envelopement and investiture at the bottom of the sea, by the substance diffused; and the disturbance of that deposit from its original level; which may probably have been accomplished by some violent convulsion of the earth. But the one may have followed the other at an immense interval of time. Had it happened soon after the animals in question perished, their tender and corruptible sub stance would have soon been so essentially altered; as to preclude all possibility of recognising them at the present day. Surely we need not anticipate objec tions from the farce required to implant the huge calcareous masses in the sides of Bolca. If racks are projected from burning craters, mountains raised, or islands formed in unfathomable seas, what power is there which violent convulsions of the earth are un able to overcome.? .
The curiosities afforded by Bolca, had, centuries ago, attracted the notice of ingenious and speculative minds; and thence the peasantry and labourers of the neighbourhood have gained a livelihood by procuring them. Blocks of moderate size are detached from the face of the quarries; and being brought out and set on edge, are split asunder with sharp hammers or wedges. The workmen then examine the leaves, to discover whether there be organic remains of fishes or other substances; and should they. discover any such, which are generally shattered from the rude ness of the operation, they collect them with the greatest care : the pieces also that adhere to the stone, are cautiously separated from it. When their daily occupatiOn is completed, the workmen carry the collections they have made to their own houses, where they are kept until delivered to their employers in Verona. The pieces are taken thither in basketS, and either given to the owner of the soil, or privately sold to dealers in such productions, or to naturalists desirous of acquiring them.' It is said that the pm: chaser, who obtains the fossils in this state from the workmen, is then obliged to employ a skilful lapidary to search. out and arrange the pieces composing each specimen, and cement them on another stone of same kind. So much art and accuracy are some: times used in doing this, that it is scarcely possible to discover the places of junction; and it is thus that the specimens are prepared for sale, or for cabinets. As a greater Or less proportion of the brown matter of the bones, fins, and other parts of fishes, some times adhere to One side in splitting the stone, and sometimes to another,. or is frequently divided be tween both, the more valuable specimens consist of duplicates • for when the pieces are well and skilfully put together, their prominences correspond with the cavities in the opposite half. Most of the specimens hitherto extracted have come from one principal quarry in the side of the hill, called Pescaia by the inhabitants of that territory; but there are several be. sides, supposed to be of later discovery, all equally abounding in petrifactions. The people, however; who attempted to form excavations being poor, and no funds being specially appropriated for this curious research, which would have been•attended with con siderable expense, nothing important followed. The soil where the quarries lie, has belonged to different owners, who were ,solicitous to obtain its contents.
The variety and singularity of the fossils discover ed on the surface and in the recesses 'of this hill, af ford so much scope for philosophical contempla tion, that unusual care has been taken to collect and preserve them. Extensive cabinets, from which all other varieties were excluded, have thence been form ed of them alone ;'and these have passed into the hands of successive owners, along with a right to ex-; pldre the soil, in the same manner as we are wont to transfer the richest territorial property. The first
cabinet of the productions of Bolca with which we are acquainted, was collected by a person distinguish ed in the pharmaceutical art, Francesco Calccolari, who flourished in the sixteenth century. He is cele + brated by Aldrovandus, Gesner, and other cotempo rary authors, for his knowledge of natural history ; and left a work on the contents of his cabinet, De scrizione de' Museo Calccolari, which was published after his decease by Andrea Chiocco. Nearly a cen tury later, Count Ludovico Moscardi, having the same propensities for study, forined a cabinet, partly_ consisting of the petrifaetions of Bolca. Still more recently, a member of the noble family of Rotari andi Count Andrea Gazola, were occupied with similar, pursuits towards the earlier part of the 18th century. The former, who died in 1744, addressed a learned' epistle to Vallisnieri, on the subject of the fishes of. Bolca ; and the latter laid the foundation of the most celebrated of all collections of this description, which still subsists in his nephew's' possession. Soon after wards, the learned Marquis Scipio Maffei, equally distinguished by his skill in polite .and antiquarian literature, as in exploring natural phenomena, pur chased. the quarries. Assisted by M. •Seguier, a. French botanist, he was long engaged in recovering the fossil remains of animals, numerous specimeni of which were dispersed among the naturalists of Eu rope. Nearly about the same time, Giacomo Spada, a priest of Grezzana, which is a place situated among the Veronese mountains, following in the .footsteps of Maffei, soon formed a respectable collection, which constantly increased during his life. When he died, in 1750, it passed into the hands of Maffei, from whom M. Seguier acquired'it ; and 14 him it was carried to the city of Nismes in France, where it yet remains. Spada published three different works on the petrifactions and fishes of the territory of Ve rona. The losd of his museum, and of the collections of Maffei to that country-,'were partly indemnified by Julius Cxsar Moreni, whose cabinet was enriched with numerous petrifactions, but particularly fisheS. The whole was on his death acquired by the Marquis Octavio di Canosia. Near to the period when the hours of Moreni ceased, those of the most celebrated of all the collectors, Vincenzo Bciza, a learned apo thecary of Verona, commenced. Twenty Years were occupied in forming his museum, which neither ex-. pence nor trouble were spared in rendering complete. He purchased the soil wherein the quarries of Bolca lie, or obtained permission from the heirs of Maffei to renew the excavations ; and, towards the year 1770, began to found a collection, from its owner denomi nated Gabinetto Bozziano, which was famed over all Europe. The activity of not less excited by his love of investigating the profound phenomena which his reseal ches tended to elucidate, than by the desire of surpassing those cotemporaries who were engaged in the like pursuits. At length his . cabinet contained 700 specimens of petrified fishes, besides many other animal and vegetable substances, recovered in the same state from the territory of Ve rona. Amidst such a number of specimens, 69 dif ferent species of fishes could be distinctly identified, setting aside others whose characteristics were not sufficiently prominent to give them an appropriate place in the arrangement. " In my cabinet," says Bozza," which contains above 600 fishes of different sizes, all extracted from Bolca, there are more than 100 whose kinds are known, which differ from each other in genera and species ; and many others besides to which similar ones have not yet been' disAlIvered alive." Juan Andres, a Spanish traveller, relates, that Bozza assured him, that he possessed eight spe cies of fishes such as now inhabit the Pacific Ocean,. and above 30 other species totally unknown ; and he saw some specimens 30 or 40 inches in length. - But' the Physical Society of Verona, on stricter scrutiny, have reduced the species to 69. In the year 1794•, this magnificent collection was purchased, at a high price, by the Count Giambattista Gazola, nephew to Count Andrea, mentioned above. The Count had him self with great industry procured fossil fishes during • of eight years, and his museum contained many specimens not to be found in that of Bozza. He likewise acquired the museum of another collec tor, the Marquis Giacopo Donisi ; so that he cane into possession of • the most splendid and extensive collections' which any naturalist had ever enjoyed. From Mount Bolca alone he had above 800 speci mens of petrified fishes, many of extraordinary-size, and of the finest quality ; and the same place afford ed him numerous petrifaetions of crabs, winged in sects, and marine plants, of which he was enabled to form a perfect series. See Societas Physicoruin Ve ronensium, Ittiolitologia Veronese del Masco Bozzi ano, 1796. Bozza Lettera al P. Orazio Rota, sulfa universale rivoluzione sofcrto dal terracqueo. Ermengildo Pini sulle rivoluzioni del globo terrestrc pi-ovenzenti azione deli' crepe, part i. ii. Spada, Disscrtazione ova si prova the li Petrificate Corpi Marini the nei monti adiacenti a Verona si trovano, non sono scherzi di natura, ne diluviani ma antedilu viani. Spada, Cmporunt lapidefactoruns agri Vero nensis Catalorrus. Testa, Lcttera su i Pesci Fossili del Monte Bolca. Fortis, Lettera at Signor Abate Testa sopra i Pesci Ischeletriti de' Monte di Bolca. Fortis, Transunto della replica al Signor Abate Tes ta sugli izziolili de' Monti •VeroneSi.. -Juan 'Andres,. Carton familiares del viage quo hizo a varias ciudades the Italia, v. 3. Maffei, Verona Illustrata, torn. iii. Conzpendio della Verona Illustrata, _ad use de' Forcs tieri, tom. i. Catologo Siste ;wilco dei piu rani Ittio liti dcl Monte Bolca, the si conservano nel gabinetto privato del Signor Vincenzo Bozza.'