§45. FOSSIL FISHES OF MONTE BOLCA. -65 



that these fresh-water deposits are the contents of a lake, 

 belonging to the newer tertiary epoch ; and that the period 

 of their formation must have long preceded the present con- 

 dition of the country, for they contain some unknown species 

 of animals, and the Rhine has worn a channel through them 

 to the depth of several hundred feet. 



45. Fossil fishes of Monte Bolca. — Another inte- 

 resting assemblage of tertiary strata is exposed in the cele- 

 brated quarries of Monte Bolca, that are situated on the 

 borders of the Veronese territory, about fifty miles NN.W. 

 of the lagunes of Venice. These deposits form part of a 

 range of hills of moderate elevation ; volcanic deposits 

 abound in the neighbouring Vicentin, and the summit of 

 the hill at Monte Bolca is capped with basalt.* This hill 

 is principally composed of argillaceous and calcareous 

 strata, with beds of a cream-coloured fissile limestone, which 

 readily separates into lamina? of moderate thickness, and 

 abounds in fishes in the most beautiful state of preservation. 

 They are all compressed flat, but the scales, bones, fins, and 

 even the muscular tissue remain ; their colour is a deep 

 brown, thus admirably contrasting with the limestone in 

 which they are imbedded. Several hundred species are 

 contained in these quarries, and thousands of specimens 

 have been collected ; according to M. Agassiz, all the 

 species, though related to the recent, are extinct. t From 

 the immense quantities which occur in so limited an area, 

 it seems probable that the limestone in which they are 

 imbedded was erupted into the ocean in a fluid state by vol- 

 canic agency ; and that the fishes w r ere thus suffocated, and 

 surrounded by the calcareous mass. Nor is this hypothesis 

 without support, for on the appearance of a volcanic island 

 in the Mediterranean, a few years since, hundreds of dead 

 fishes were seen putrid and floating in the waters ; and it 



* Organic Remains of a Former "World, vol. iii. p. 247. 

 f See Recherches sur leg Poissons Fo&siles. 



