336 



THE GEOLOGIST. 



sented the Neocomien formation ; which is also the case in 

 the Gulf of the Loire and the northern parts of the country, 

 where the other portions of the Cretaceous formation are so 

 well developed. If we now compare with each other the 

 three local faunas of the Neocomien formation which I have 

 noticed above^ we find that they comprise, at present, in the 

 Proven9al basin, sixty-eight species; in the basin of the 

 Seine, eleven species, or al)out a sixth of the number ; and 

 in the Jura, eight species, or less than an eighth of the num- 

 ber in the Provenpal basin. These numbers alone, without 

 regarding form, ought to prove either a greater development 

 in the Neocomien epoch of Provence, or a distinct fauna, 

 indicated by the greater number of the species. I am of 

 opinion that both causes existed, and that the species will 

 demonstrate it, by the following comparison of the three lo- 

 calities. 



1st. In the Proven9al basin, I find in the lower beds of 

 the Neocomien, fifty-one species of which /oz^r, A. difficilis, 

 Leopoldinus, cryptoceras and radiatus, are also found in the 

 Paris basin, and six, A. astierianus, cryptoceras, Carter oni, 

 Castellanensis, Leopoldinus and radiatiis, in the Jura. Hence 

 there remains, after the species common to more than one 

 basin, forty-four species at present peculiar to the Proven9al 

 basin, in the lower beds of the Neocomien. 



I have stated that I am acquainted with seventeen species 

 from the upper beds of the Provenpal basin, of which, one 

 alone, A. Nisus, is common to the Parisian basin, and none 

 to the Jura; hence, sixteen species are peculiar to the Pro- 

 venpal basin. 



From these facts we must conclude that at the epochs of 

 the lower and upper Neocomien, the Proven9al basin was 

 separated from the Parisian, since, though both present 

 common species which indicate the identity of the strata, or 

 contemporaneousness of the two seas, the faunas show a great 



