338 



THE GEOLOGIST. 



basin to establish a fauna different from that of Pro- 

 Yen ce. 



3rd. By comparing the species of the Jura with those of the 

 Provengal basin, I find in the lower strata, six species com- 

 mon to both ; I find three also, common to the Paris basin^ 

 and only one, A. Gevrilianus, entirely distinct ; in the upper 

 strata I am only acquainted with one species common to the 

 Paris basin. 



Allowing that there are some differences between the spe- 

 cies of the Jura and Paris basins, if I may judge from the 

 other organized bodies found in each, there has been a per- 

 fect identity in the fauna, which we may perceive by the 

 species of Ammonites common to both ; thus, judging from 

 the fossils, I should consider the Neocomien deposit of the 

 Jura as forming part of the same sea as the Neocomien for- 

 mation of the Paris basin. 



The conclusions I arrive at, regarding the Neocomien for- 

 mation are the following : that at the time of the formation 

 of this Group of the Cretaceous formation in France, there 

 were two basins, or two contemporaneous seas, the Proven- 

 §al and Paris basins, whose faunas, although having many- 

 species in common, were certainly each more zoologically 

 distinct than the Mediterranean and the Atlantic of the 

 present day; that at this epoch, either from the whole hav- 

 ing been raised in equal proportion, or from there not being 

 an aqueous basin in the present basin of the Pyrenees and 

 the Gulf of the Loire, they do not show, at present, any 

 positive trace of the lower Neocomien formation ; that these 

 seas, which were distinct at the period of the first deposits 

 of the Neocomien formation, preserved the same conditions 

 to the end of this geological group, is distinctly indicat- 

 ed by the faunas ; lastly, that the Provengal basin has, at 

 the same time, a much greater development of the strata 



