312 A. J. Juices- Brou-iie — 'Deo Stages in Upper C/uilk. 



No definite conclusions can be based on the above list, becnuse so 

 few species of Ceplialopoda have yet been found in the zones of 

 0. 2)ilulc(, and A. quadratus ; but so far as the evidence goes it confirms 

 that of the German Cephalopoda, for not one of the species ocourrino- 

 in the four lower zones ranges up into tlie higher. Tlie zone of 

 B. miicronata comprises nineteen species, and this fauna is completely 

 different from that of the beds below the quadratus zone. 



I liave also tabulate'] tlie distribution of the Ceplialopoda which 

 occur in the corresponding zones of the South of France, Ammonoids 

 being fairly numerous in some areas, especially in the Charentes, 

 the Bordelais, and the Pyrenees. The deposits of Southern France 

 differ so much from those of the northern area that the same zonal 

 terminology is not applicable. Coquand, however, established 

 a number of sub-stages which have again been subdivided by Arnaud, 

 the result being a series of 'assises' which are practically zones. 

 From the tabular view of these divisions and their principal fossils 

 which has been given by de Grossouvre (op. cit., p. 383, table xiv) it 

 is easy to correlate Ariiand's lettered zones with those of the Paris 

 Basin, and from this source I have compiled a separate table of the 

 Senonian Cephalopoda. 



To print this table would unduly increase the length of this essay, 

 but I may state some of the facts which are thus brought out. The 

 most important fact is the obvious existence of two different faunas, 

 the four lower zones having yielded no fewer than fifty-three species 

 of Cephalopoda, and not a single one of them ranges into the two 

 higher zones (i.e. of A. quadratus and B. mucronata), although these 

 have jointly produced twentj'-eight species. From the zone of 

 Placenticeras hidorsatum, the equivalent of our 0. pilula zone, eleven 

 species have been obtained of which three are restricted to it, while 

 all the rest range down into the zone below (that of Placenticeras 

 sj/rtale), and none of them range upwards. Here, therefore, the plane 

 of division between the two stages is clearly marked. 



England is considered last because so few species of Cephalopoda 



