LYELL ON THE MIOCENE BEDS OP N. AMERICA. 423 



now living on the globe. The large Pyrulce of the sub-genus 

 Fulgur, and several other forms above enumerated, list, p. 419-20., 

 would enable a conchologist, only acquainted with recent shells, 

 to distinguish a set of American from a set of European miocene 

 fossils. The genera Pholadomya and Gnathodon, and several 

 others found in the miocene beds of the United States, would also 

 enable the conchologist to recognise the American type. 



It is worthy of remark, that the recent shells found in the 

 American miocene beds are not only in about the same proportion 

 to the extinct as is observed in the Suffolk crag or in the faluns 

 of Touraine, but they also agree specifically in most cases with 

 mollusca now inhabiting the neighbouring Atlantic. Now most 

 of the recent miocene species of Touraine agree with species now 

 living on the western coast of France or in the Mediterranean, 

 and those of our crag are identifiable with species living in the 

 British seas. This result appears to me to confirm the accuracy 

 of the conchological determinations, for if any one of those paleon- 

 tologists who are unwilling to believe that species pass from one 

 geological period to another, should maintain that the living species 

 are so numerous, and often resemble each other so closely, that 

 false identifications may easily have arisen, I reply, that in that 

 case, according to a fair calculation of chances, nine-tenths of the 

 American miocene species said to be recent ought to have been 

 identified with exotic species, instead of being found to agree with 

 members of that very limited fauna at present known on the 

 American shores. The same argument is clearly applicable to 

 the identifications which have been made of fossil and recent shells 

 in the European miocene formations. With the exception of one 

 Calyptrcea, I find no one of the miocene shells which I have iden- 

 tified with recent species to be identical with shells of the Pacific. 

 The analogy is to an Atlantic, not a Pacific fauna. 



Among other points of analogy between the miocene fossils on 

 the banks of the James River and those of Touraine, I ought not 

 to omit mentioning the multitude of large shells of the genus 

 Pecten, as P. Jeffersonius and others, occurring near Williamsburg, 

 (Maryland,) just as the large Pecten Solarium occurs in the faluns 

 of the Loire near Doue. Nothing similar is observed in the eocene 

 fossils, whether European or American. The same may be said 

 of the large and conspicuous shells of the genus Panopcea, found in 

 our Suffolk crag, and in the American miocene beds, but not in the 

 older tertiary strata. 



As it is very rare to meet with any land or freshwater shells in 

 the red and coralline crag of Suffolk, so are they almost unknown 

 as yet in the American strata of the same age. The Gnathodon, 

 an estuary shell, has been found in several places, and I met with 

 two odd valves of a Cyrcena, well preserved in the miocene strata 

 of Petersburg, Va. The species is rather larger than C. consobrina 

 from the Nile. The Buccinum quadratum of Conrad, doubtless 

 a marine shell, might easily be mistaken for a Melanopsis. 



Even in Touraine, where the bones of mammalia are not un- 



