Vol. 52.] 



A DELIMITATION OF THE CENOMANIAN. 



125 



is little difference between its fauna and that of the beds below. 

 Cephalopoda are rather more abundant, but are of the same species ; 

 Holaster subglobosus becomes common about 8 feet below this bed 

 and ranges above it, at the same time Epiaster crassissimus and 

 Catopygus carinatus either die out or become rare. The following 

 is a list of the commoner fossils occurring in this central part 

 of the Cenomanian, the first column showing those in Bed 6, and 

 the second those in Bed 7. The letter L indicates species which are 

 given on the authority of M. Lennier : — 



Porosphcera, sp 



„ urceolata . . 



Bhynchonella convc.va .. 

 „ dimidiata 



„ Grasiana 



Kingena lima 



Terebratula arcuata 



„ capillata .. 



Terebratella Menardi .. 



Caratomus rostratus 



Catopygus carinatus 



Cidaris vesiculosa 



Holaster carinatus 



Epiaster crassissimus ... 



„ distinctus 



Pseudodiadema ornatum 

 „ BenetticB 



Discoidea subucula 



G lyphocyphus radiatus... 



Salenia petalifera 



sp 



Exogyra conica 



m 



Ostrca canaliculata {lateralis) ... 



Pecten asper , 



„ Galliennii , 



,, Marrotianus , 



„ Puzosianus , 



,, elongatus , 



Janira cequicostata 



„ quinquecostata , 



Lima clypeiformis 



Spondylus striatus 



Pleurotomaria Arckiaci , 



Avellana cassis , 



Aporrhais, sp., cast 



Ammonites falcatus 



„ Mantelli , 



„ varians 



„ Coupn 



Turri lites cost a tus 



„ tuberculatus 



Scaphites cequalis 



Hamites sp., 



Nautilus, sp 



* 

 * 

 •x- 

 * i * 

 * ! * 

 ... » 



Bed 8. 



Above the phosphates the chalk is featureless. It is, however, 

 distinctly whiter and more free from glauconite ; flint-like cherts 

 continue to divide it into courses. Fossils are comparatively rare ; 

 we collected none from it. 



The Turonian. 



The base of the Turonian is well marked between St. Jouin and 

 Brunval by a bed of hard nodular chalk, like that which we 

 recognize in England as the Melbourn Rock. In fallen blocks on 

 the shore fossils common to the base of the Middle Chalk occur 

 plentifully, such as : Inoceramus labiatus, ffliynchonella Cuvieri, 

 Cardiaster pygmceus. 



