IN THE TERTIARY FORMATIONS. 217 



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 witbiii 

 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 IMartre 

 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 re- 

 ferred to a very recent local lacustrine deposite. M. Agas- 

 siz assigns them to the second period of the Tertiary for- 

 mations, 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 Mont 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-apenninc formation, as far as they arc yet known, 



* M. Agassiz has rc-arrangcd these Fishes under 127 Species, all ex- 

 tinct, and 77 Genera. Of these Genera 38 are extinct, and 39 still living: 

 the latter present 81 fossil species at Monte Bolca, and the former 4fi 

 species. These 39 living Genera appear for the first time in this forma- 

 tion. 



VOL. I. — 19 



