580 



J. E. BLAKE OlSr THE TIPPER 



nia-grits of Havre, with any Ostrea-deltoidea beds above them, have 

 well-marked features of their own. 



There cannot be any doubt of the correspondence of these beds to 

 those called Astartian throughout the whole of the southern range ; 

 and from this it follows that the Kimmeridge passage-beds of Wey- 

 mouth are the exact representatives of the same portion. It seems 

 also most satisfactory to place the Abbotsbury and Westbury iron- 

 stones in the same horizon, as they are apparently higher than 

 Supracoralline. The lowest beds of the Kimmeridge Clay seen in 

 the Wootton-Bassett cutting, with Rhynchonella inconstans, and the 

 great Ostrea-deltoidea beds of Lincolnshire, belong here also. 



On the south bank of the Seine, it is probable that at Honfleur 

 Pterocerian beds may be developed, though not well seen ; but the 

 great mass of the clay at the Cap du Heve belongs to this division — 

 that is, the " Marnes a Pteroceres " of Dollfus, and the beds nos. 7 

 to 14 of Lennier. In spite of the abundance of Exogyra virgula, 

 and even of Terebratula Leymerii in certain beds, this portion is 

 well marked palseontologically by its numerous Pterocerata. The 

 Ammonite-marls above, so far as seen, belong to the Yirgulian. 



Doubtless the same subdivision might, with care, be made at Wey- 

 mouth ; but as yet, in spite of the many collectors who formerly 

 searched the shore, no Pterocerian fauna has been brought to 

 light. The Kimmeridge Clay of England has been shown to 

 be divisible into two groups*, formerly called Upper and Lower 

 Kimmeridge. The term Kimmeridgian must now be confined to 

 the latter ; and though the subdivision into Pterocerian and Vir- 

 gulian is not very clear, it may, perhaps, fairly be taken that the 

 absence of Exogyra virgula (as in Lincolnshire), indicates the former, 

 while its abundance (as at Ely, Swindon, and in parts of the south- 

 ern coast section) indicates the latter. The idea expressed in the 

 paper quoted, that the Lower Kimmeridge Clay represented the 

 Astartian, was founded on the abundance of an Astarte which at 

 least is very like A. swpracorallina. It may, however, be distinct ; 

 and in any case its presence cannot be allowed to interfere with 

 stratigraphical conclusions supported by the general palseontological 

 facies. 



In the Boulogne area we have the same difficulty in drawing the 

 lower limit as at Bourges. While, on the one hand, there need be 

 no hesitation in including the Gres de Wirvigne in the Astartian, 

 or the Mont-des-Boucards marls in the Supracoralline, the three 

 intervening deposits are doubtfully attached either to one or the 

 other. It is certain that, in the Meuse, Buvignier would include 

 such beds as the Ostrea-deltoidea clays in the Astartian ; yet the 

 ferruginous bed above with Trigonia Bronnii seems to unite both, 

 through the Normandy sections, to the Supracoralline, as has been 

 seen above, p. 563. The important Nerincea-oolite, again, is con- 

 nected with the lower series by the abundance of that genus, nowhere 

 characteristic of Astartian, but constantly found in Supracoralline 



* Quart. Journ. Geol. Soc. vol. xxxi. p. 197. 



