126 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Tablh 



{continued). 



















Rang 



e of species. 







London area. 





Paris 



area. 





Belgian 

 area. 







m 



13 



i 













Pisces, &c. of the Barton Clay. 



on 



§ 



u 



i 



5 



c 

 o 



a 

 o 



pq 



cq 



'3 



O 



O 



13 



w 



O 



o 

 Is 





13 

 M 



s 



CO 



c 



o 



CS 



o 



s 



to 





A. 



B. 



D. 



A. 



c. 



D. 



E. 



D. 



E. 



Reptilia. 















Chelone 















! 







Pisces. 



Lara na 





* 

 * 

















Myliobatis marginalis, y/^. 



nitidus, Aq 



iEtobatis subarcuatus, Ag 





Notidamus serratissiiuus, Ag 





1 









1 



§ 5. Concluding Remarks — Physical conditions prevailing at the 

 Paris Tertiary Period. 



I have named that portion of the Eocene series, of which the 

 foregoing deposits form the centre and type, the " Paris Tertiary 

 Group *," because it is in the Paris area that this group is most 

 complete and best exhibited, and that the animal life of the period 

 has been most perfectl}^ developed. Of marine Testacea alone above 

 1200 species existed in the French areaf, whilst in the English area 

 they were apparently but about half that number. A somewhat 

 similar proportion appears to hold good with respect to the Corals, 

 Echinoderms, and Foraminifera ; but of Fishes, Reptiles, and Crus- 

 tacea, the English series shows a considerable preponderance. 



The Paris group originated, as I have before mentioned, with 

 the period of the Lower Bagshot Sands and Glauconie moyenue in 

 the subsidence of a southern land and extension of the sea % over 

 the previously littoral and dry portions of the Paris district, leading 

 to the introduction of the Nummulitic fauna and of forms indicating 



* This is nearly synonymous with M. Ale. D'Orbigny's " Systeme Parisien," but 

 he includes in this the '• London Clay" and excludes the " Lits Coquilliers ; " 

 whereas I consider the London Clay older than the Lits Coquilliers, and as the 

 centre of another (the London) group ; the Lits Coquilliers and Glauconie moy- 

 enne I would place in the Paris group. 



t The supplement now in course of publication by M. Deshayes for his great 

 work on the Fossil Shells of the Paris Tertiaries promises to add largely to the 

 number already known — even to the extent of nearly doubling that number. 



% I think it probable that the sea of the London area became connected at 

 this period with a southern sea by the depression of the intermediate land. 



