XXXVl PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



much too few to imply a cretaceous age for the strata in question, or 

 even a zoological passage from the cretaceous to the tertiary forma- 

 tions. They who have read with care the successive numbers of the 

 * Bulletin ' of the Geological Society of France, are aware how much 

 that body has been occupied with the same problem, and how 

 steadily the evidence in favour of the same important conclusion has 

 been gaining strength. M. d'Archiac, writing in 1847 on the fine 

 collection of Biaritz shells submitted to his inspection by Mr. Pratt, 

 observed that forty-eight, or one-fourth of the whole series, were 

 identical with fossils of the lower eocene of the Paris basin, while the 

 rest were all tertiary forms except four, which belonged to species of 

 the chalk*. In a paper by M. Deshayes, read to the Geological 

 Society of France in June lS44f, that able conchologist declared, 

 after examining the Biaritz fossils, " that the whole of the num- 

 mulitic system must be classed as tertiary ; an opinion confirnftitory,'^ 

 he said, " of the results previously arrived at by M. Leymerie in the 

 Corbieres, and of M. Bertrand Geslin in the Alps." Lastly, I may 

 observe, that you will find similar opinions recorded in the 'Bulletin,* 

 either in the memoirs or verbal comments of MM. Deshayes, Charles 

 Desmouiins, Raulin, Leymerie, Tallavigne, Delbos, Desor, Boue, 

 Archiac, and Alcide D'Orbigny, all published in the course of the 

 last six years. Whether a real transition from the cretaceous to the 

 tertiary strata can be made out, is a point which has also been fully 

 discussed, and how far the Maestricht beds are represented in the 

 Pyi'enees. It appears from the researches of MM. Desmouiins and 

 Baulin, that some few of the characteristic fossils of Maestricht 

 have really been found in that chain ; but you will, I think, agree 

 with M. Deshayes, that they are not enough to establish the exist- 

 ence of any true equivalent of the Maestricht group — that distinct 

 and uppermost division of the chalk to which the Faxoe coralline 

 limestone in Seeland, as well as the pisolitic strata of Sezanne near 

 Paris, are referable. 



When we consider that the age of the nummulitic formation of the 

 Pyrenees, however clearly it may now be determined to be tertiary, 

 has been regarded by so many able authorities as a subject of perplex- 

 ity and debate up to so late a period, we cannot feel surprised that 



* Bulletin, vol. iv. 2nd Series, p. 1006. 



t Translated in (^uart. Jpigrn. Qeol. Soc. 1845, p. 111. 



