210 Alfred Bell — The Succession of the Crags. 



Plaisancien and Astien (Lower? Pliocene) stages, the progress of 

 geological science demands the intercalation of other groups. Prof. 

 Sequenza has described an extensive deposit in Sicily and S. Italy, 

 intervening between these two stages, termed by him " Zancleano." 

 With this stage may be correlated the following deposits, i.e., — the 

 Marne Vaticano near Eome, the Lower Val d'Arno near Florence, 

 Montpellier in France, on both banks of the Tagus near Lisbon, 

 in Andalusia and Catalonia (?) in Spain, at Salles in the Gironde, 

 the Bolderberg Hill in Belgium, and probably some of the Holstein 

 and North German beds. These beds appear to be the oldest Pliocene 

 deposits of Western Europe. 



Succeeding these, occur the horizons to which appertains the sub- 

 Appenines of Italy, Sicily, Dauphiny, and Provence (both marine 

 and freshwater), the blue marly clays of Malaga,^ the so-called 

 Crag of Normandy, the Sables noirs of Belgium and Guelderland in 

 Holland, and probably the ferruginous ironsand extending at in- 

 tervals for nearly 200 miles^ from the hills near Dorking, in Surrey, 

 through N.E. France and Belgium to Holland. 



Favoured by Sir Charles Lyell, I am able to supply a geological 

 want, i.e. the list of species collected by him in the aforesaid Norman 

 Crags. Comparison will show that they belong to an older stage 

 than any of the English Crags. 



Astarte Omalii *Cerithium, sp. 



*Cytherea, sp. *Eulima 



Kellia ambigua ? Murex excul/pta 



*Ledapella Natica proxima 



Lucina borealis „ hemiclaiisa 



Mactra subtruncata ,., 



Nucula nucleus * 11 2 sp. 



? , Nassa prismatica 



Ostrea edulis „ reticosa 



Pecten opercularis ,, grajiatina 



* „ Philippii * „ gibbosula 

 Solen *Patella, sp. 

 Thracia pubeseens ?Iiissoa 



* Venerieardia fJouannetti ?J Troehus bullatus 

 Calyptrea chinensis „ ziziphynus 



* Crepidula gibbosa * Turbo exarata 

 Cerithium tricinctum Valuta Lamberti 



In addition to these, M. Hebert gives Axinus flexuosus, Astarte 

 mutahilis, Corhula gibha, Mactra arcuata, ^'•'Crepidula unguiformis, 

 *•' Chemnitzia gracilis (BroG.) , Natica millepunctata, '■■' Turritella vermi- 

 cularis, and Nassa propinqua. These are all that are known from 

 the Norman Crags. 15 out of the 44 (thus marked ^•') being absent 

 from the English Crags. 



The ironsands are generally unfossiliferous ; this, I presume, is 

 owing more to their physical composition than to original poverty of 

 life, as from the box-stones and the Lenham sands I j)Ossess a list 

 of 86 forms referable to 67 genera, indicating a richer fauna than 

 is generally supposed. 



Halloy has provided for these sands, by supposing them rather 



1 See the interesting series, collected by Mr. H. "Woodward at the Tejares, Malaga, 

 in 1860, preserved in the British Museum. 



