JtTKASSIC OF THE PARIS BASEST . 



563 



P. Protei, Ceromya excentrica, Pinna pesolina, Pecten midas, and 

 Rhynchonella corallina. Prom this oolite are also recorded Cidaris 

 jlorigemma and Hemicidaris intermedia. All the more important 

 fossils except the Pholadomyce come up from below and finish in 

 this bed. It is, however, coloured on the geological map with those 

 above it as belonging to the " Astartian." It is denoted by P 1 of M. 

 Pellat. The succeeding beds P 2 and P 3 , are comparatively unfossi- 

 liferous ; but their fossils are such as would unite them rather to the 

 overlying than to the underlying beds, Ostrea deltoidea and Trigonia 

 papillata being the chief recorded. The Gres de Wirvigne, assimi- 

 lated by M. Pellat to the Trigonia-grits of Havre, is somewhat dif- 

 ferent from them in mineral character, being more siliceous and full 

 of oysters ; it has a thickness of 6 feet, and is overlain by marly beds 

 with hard bands. The fossils observed — Ammonites Berryeri?, 

 Purpura sp., Leda venusta, Astarte supracorallina ?, Corbida Des- 

 hayesea, Trigonia Meriani ?, Cyprina cyreniformis, Pleuromya tellina, 

 Pecten solidus and P. strictus, as well as others recorded, such as 

 Ammonites erinus, Lucina substriata, L. rugosa, Pinna granulata, 

 Exogyra virgida, Terebratida subsella, Pygurus Blumenbachii, Phab- 

 docidaris Orbignyana — all have a tendency to confirm M. Pellat's 

 conclusion ; and scarcely one is more connected with beds below than 

 with those above. It is possible that these grits and associated 

 beds represent more than the Trigonia-grits of Havre and Wey- 

 mouth, since there is nothing above them that can be called Ptero- 

 cerian. 



The overlying beds, in fact, are seldom seen. On the hill-slopes 

 south of Mont Lambert but little can be made of them ; and the 

 same is the case in the north, near Bazinghen. At Boulogne they 

 are hidden beneath the town, and merely a part is exposed at Breque- 

 recque, end contains no fauna which can be specially called Pteroce- 

 rian. It is perhaps scarcely worth while to separate these beds from 

 the overlying ones, called H and I ; but we may usefully charac- 

 terize this lower mass by the presence of Ammonites orihoceras, which 

 is associated with Thracia depressa, Lucina minuscula, Pholadomya 

 acuticosta, Area teccta, Gervillia kimmeridiensis'?, and Anomia sp.; 

 it then represents the zone of that Ammonite, and will be assi- 

 milated to Pterocerian beds elsewhere. The succeeding series 

 commences with a very characteristic group of rocks, part of which 

 forms a great bank with white veins on the shore north of Boulogne : 

 and 18 feet of it is quarried along the sides of the great valley be- 

 tween Mont Lambert and the sea. It is everywhere fossiliferous, 

 the most abundant fossils being Ammonites longispinus, Trigonia 

 Rigauxiana, Pholadomya acuticosta, Gervillia Jcimmeridiensis, Exogyra 

 virgida, Terebratida subsella, and Serpida tetragona. This bed forms 

 the base of a series of great thickness, in the centre of which comes 

 the conspicuous mass of soft sand with large cheese-doggers (L of 

 M. Pellat, 33 and 34 of M. Hebert), which is only seen at La Creche. 

 This makes no show on Mont Lambert, and is probably quite a local 

 deposit. Por purposes of comparison it is well to pass over these 

 minor distinctions, and to place all the mass K L M of M. Pellat in 



2p 2 



