370 A. J. Jukes-Bronne — Tivo Stages in Upper Chalk. 



were definite stratigrapliical units, and de Mercey was wrong in 

 supposing that the Coniacien had no separate existence. The 

 Santonieti was not therefore the equivalent of the whole " Seuonieu 

 Inferieur" as he supposed. Moreover, French geologists were so 

 accustomed to the use of the name Senonian in its wider and more 

 comprehensive application that the idea of its restriction to a portion 

 of the original stage did not commend itself to them. Hence 

 a complicated system of stages and sub-stages was adopted, which 

 included an unnecessary number of names and could not possibly 

 be used with advantage in any other country. The following table 

 shows the divisions recognized bv de Grossouvre in 1901 : — ^ 



Stages. 

 Danien 



Senonien 



turonien 

 Cenomanian 



Sub-stages. 



r Campanien 



I Corbierien 



/ Angoumien 

 t Saumurien 

 (not divided). 



Assises. 



/ Superieur. 

 ( Inferieur. 

 / Santonien. 

 \ Coniacien. 



It is obvious that this scheme is illogical ; the Corbierien and 

 Campanien have the same paleeontological and stratigraphical value 

 as the Turonian, and consequently the retention of a comprehensive 

 Senonian can only produce confusion and raisa^^jirehension. This 

 seems to have been perceived by de Lapparent, for in the latest 

 edition of his Traite de Geolngie he remarks (p. 1883) that "The 

 old Senonien of d'Orbiguy really includes two very distinct faunas of 

 Cephalopoda, Mortoniceras and Placenticeras prevailing in the one 

 which is the fauna of the Emscher mai'ls of Westphalia. The other 

 fauna, in which Pachjdiscus and Baculites are conspicuous, is that 

 of the Chalk of Haldem and Lemberg and of the beds near Tercis. 

 The beds which contain it form the Aturien stage, from the Adour on 

 the banks of which this division is well developed". 



De Lapparent therefore divides his Upper Cretaceous Series into 

 six stages, for which he adopts the names Cenomanien, Turonien, 

 Emscherien, Aturien, Danien, and Montien, thus excluding the 

 Albien and including the Montien, which others regard as the base of 

 the Eocene Series. The stages with which we are concerned he 

 subdivides in the following manner: — 



Stages. 



Aturien 



Ejischerien 



Sub-stages. 

 i Maestrichtien 

 (^ Campanien 



r Santonien 

 (Coniacien 



Zones. 



Calcaire a Baculites. 

 J Craie de Meudon. 

 ICraie de Eeims. 

 ( Craie a Marsiqntes. 

 \ Craie a M. coranguinum. 



Craie a N. cortestudinarium. 



From this it is evident tliat de Lapparent wished to abandon the 

 term Senonian altogether instead of adopting the view advocated by 



^ " Eechercbes sm- la Craie Superiem' " : Mem. Carte Det. de la France, 

 fasc. ii, table after p. 700. 



