FROM THE TERTIARY OF VIRGINIA. 



231 



tains between thirty and forty per cent, of recent shells. Yet the Miocene of Peters- 

 burg has not a single species which can be identified with any of the Claiborne Eocene 

 fossils, while it abounds in shells which are found, at other localities, in company with 

 more than twenty per cent, of recent species. These few facts will sufficiently exem- 

 plify the fallacy of attempting to classify our Tertiary by the rules which regulate that 

 of Europe. 



It may, perhaps, be deemed not irrelevant to this subject, to introduce here the fol- 

 lowing table of the number of the species in each genus, hitherto described from the 

 Tertiary of the United States. Unfortunately great confusion exists in their synonymy, 

 and he who would review the descriptions of them, with an impartial and unsparing- 

 hand, would confer a great benefit on all interested in American geology. To this part 

 of the subject, I have not pretended to pay any attention, and therefore the number of 

 species is, in reality, smaller than that given here, many of them being repeated under 

 the same or different genera. I, however, have not felt inclined, at present, to undertake 

 the Augean task of clearing away the synonymes, but I hope that, as far as I pretend 

 to go, I shall be found correct; that is, as far as the mere numbers are concerned.* 



List of the Fossil Shells found in the Tertiary Beds of the United States. 



Genera. 

 Acteon, . 

 Aligena, 

 Amphidesma, 

 Anatina, 

 Ancillaria, 

 Anolax, 

 Anomia, . 

 Area, . 

 Artemis, . 

 Astarte, 

 Avicula, . 



Balanus, 

 Bissomya, 

 Bonellia, 

 Buccinum, 

 Bulk, . 

 Bullina, . 



Calyptrea, . 

 Cancellaria, 

 Capulus, 

 Cardita, . 

 Cardium, . 

 Cassis, . 



No. of species. 

 . . 2 



5 



. . 7 

 1 



. . 7 

 . 51 



. . 1 



. 3 



. . 1 



1 



. . 1 



1 



. . 1 



. 6 

 . . 2 



1 



. . a 

 i 



. . 27 

 . 2 



18 



* I regret that I have not been able to obtain the names of the species figured by M. Lesueur from the Eocene 

 of Walnut Hill, Mississippi. I have seen the plates, but I do not know whether the descriptions were ever pub- 

 lished. It may be seen that I have included in this catalogue the species described in the following pages 



