Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/221

 Rh takes place in the character of fossil Fishes, not less striking than that in fossil Shells.

The fishes of Monte Bolca are of the Eocene period, and are well known by the figures engraved in the Ittiolitologia Veronese, of Volta; and in Knorr. About one-half of these fishes belong to extinct genera, and not one is identical with any existing species; they are all marine, and the greater number approach most nearly to forms now living within the tropics.

To this first period of the Tertiary formations belong also the Fishes of the London clay; many of the species found in Sheppy, though not identical with those of Monte Bolca, are closely allied to them. The Fishes of Libanus also are of this era. The Fishes in the gypsum of Mont Martre are referred to the same period by M. Agassiz, who differs from Cuvier, in attributing them all to extinct genera.

The Fishes of Oeningen have, by all writers, been referred to a very recent local lacustrine deposite. M. Agassiz assigns them to the second period of the Tertiary formations, coeval with the Molasse of Switzerland and the sandstone of Fontainbleau. Of seventeen extinct species, one only is of an extra-European genus, and all belong to existing genera.

The gypsum of Aix contains some species referable to one of the extinct genera of Monte Martre, but the greatest part are of existing genera. M. Agassiz considers the age of this formation as nearly coinciding with that of the Oeningen deposites.

The Fishes of the Crag of Norfolk, and the superior Sub-apennine formation, as far as they are yet known,