AMMONITES.— ZOOLOGICAL, ETC. 



343 



eies. A, Archiacianus^ Guersanti, Mosensis, Michelinianus, 

 Puzosiams, quercifolius, and Raulinianus, peculiar to Ar- 

 dennes and the Meuse. The upper beds afford seven spe- 

 cies, all found, without exception, in the Parisian basin and 

 the Jura, and five common to the Provencal basin. From 

 these facts it may be concluded with great probability, that the 

 Ardennes, from the species in the upper beds, are identically 

 the same as the Parisian basin, of which they appear to have 

 formed a portion, having, as at Wissant, a thin portion of 

 the lower beds, containing a number of species peculiar to 

 this locality. 



In conclusion, at the period when the Gault formed these 

 first deposits, at Wissant, Ardennes and the Meuse, this 

 basin was, at least, as distinct from the Proven 9al basin, as 

 at the period of the Neocomien. The two seas had slight 

 communication as is indicated by the species ; but the nume- 

 rous dislocations which caused the successive denudations 

 so remarkable at this period, indicated by the species carried 

 along with them, prove that there were then some ruptures 

 between the basins, and that more numerous communica- 

 tions were established ; nevertheless, the cretaceous Gulf of 

 the Loire as yet contained no Gault, and it is with doubt 

 that I cite this group, and only at the most southern part of 

 the Pyrenean basin, joining the Proven9al basin. These 

 communications, established between the Provenyal and Pa- 

 risian seas, are clearly indicated by the great number of spe- 

 cies common to both at the epoch of the upper Gault, differ- 

 ing greatly from the number obtained in the anterior periods, 

 and proving a notable difference in the specific composition of 

 the faunas, which, nevertheless, still preserve distinct species 

 in each basin. The basin of the Pyrenees, and the creta- 

 ceous Gulf of the Loire, are found at the termination of the 

 Gault, in the same condition as at the commencement of 

 this epoch. 



