80S A. J. Jtikca-BroH-no — Tico Stages in Up2^er Chalk. 



of 0. pilida in the Anglo- Parisian region, but in Germany this 

 Echinid is only found in the overlying zone of A. quadrattis, so that 

 it cannot be used as an index, and Scaphites binodosus may be adopted 

 instead. A. gramdatus ranges tliroughout these marls, which are 

 often called the ' granulaten-kalk '. 



The Ober-Senon of Schliiter, i.e. the zones of A. quadratuR and 

 B. mucronata, corresponds with the rest of the English Upper Chalk. 

 The equivalence of these zones is shown in the following table, in 

 which I have also inserted the Ammonite zones established by 

 de Grossouvre as an international basis of comparison : — 



England. 

 B. nnicronata 



France. 

 B. mucronata. 



Germany. 

 B. mucronata. 



A. quadratus. 

 Off aster pilula . 

 Marsupites. 



M. coranguinum. 



M. cortestudinarium 



A. quadratus. 

 Offaster pibila . 

 Marsupites. 



A. quadratus. 

 S. binodosus. 

 Marsupites. 



M. coranguimim. Emschcr marls. 



M. deci/piens. I. Ctivieri. 



Ammonite Zones. 



iPachydiscus neubergicus. 

 \Hoplites Vari. 



Mortonicerasdelawarense. 



Placenticerasbidorsatum. 



P. syrtale. 

 f Mortoniceras texanum . 

 \M. emscheris. 



Barroisiceras Haber- 

 fellneri. 



The reader will now be able to understand the zonal arrangements 

 employed in the following tables and to appreciate the evidence 

 thus presented. It will be convenient to begin with that of the 

 Cephalopoda, and the first table shows the distribution of these fossils 

 ill the North of Germany, where they are more abundant than in 

 England or France. This table has been compiled from that given by 

 M. de Grossouvre in 1902 ' with the correction of a few misprints and 

 mistakes : — 



TABLE I. 

 Cephalopoda of the Upper Chalk in North Germany. 



• "Eecherches svu- la Craie Superieur " : Mem. Carte Det. de la France, 

 fasc. ii, p. 700. 



