258 
THE CRETACEOUS ROCKS OF BRITAIN. 
A perusal of the above list will show that almost all the fossils 
which occur in the Cenomanian zones of Am. Mantelli and Am. 
rotomagensis at Vimoutiers, occur also in our Lower Chalk or in the 
more arenaceous deposits of Devonshire, which are believed to 
represent the Chalk Marl. A personal examination of most of the 
species above quoted has resulted in some alterations and correc¬ 
tions of the lists formerly given, and I have no doubt that a more 
thorough comparison of French Cenomanian species with English 
fossils would result in the identification of many other fossils which 
now bear different names. 
There are, as might be expected, a few species which seem to 
be restricted to western France, such as Hemiaster bufo, Rhyn- 
chondla lamarckiana, Trigonia crenuiata, Pinna Calliennei, and 
Fusus Espaillaci. There are also some species which might have 
been expected to occur but have not yet been recorded from the 
Orne or Sarthe, such as G-alerites castanea, Holaster subglo- 
bosus, Terebratula semiglobosa , Echinocyphus difficilis, Rhyncho- 
nella mantelliana, and Plicatula inflata. But it will be seen that 
the Cephalopods are entirely those of our Lower Chalk. 
Remarks on the Correlation of the Cenomanian and the Lower Chalk. 
In the preceding pages we have given a brief account of the beds 
which are regarded by Mr. Hill and myself as the equivalents of 
the Lower Chalk of England, but it should be stated that this view 
when published in 1896 was in opposition to that held by French 
geologists. They had always supposed that a large part of their 
Cenomanian was represented in England by our Upper Green¬ 
sand, and as regards the Cenomanian of Havre in particular it 
was generally supposed that the lower beds in which Pecten 
asper is common were equivalent to those which Professor Barrois 
had grouped as the zone of Pecten asper—i.e., the Chert Beds of 
Warminster, Dorset, Devon, and the Isle of Wight. 
This supposition, however, was not based on any detailed com¬ 
parison of the two sets of beds, but seems merely to have arisen 
from the existence of certain points of similarity between the Ceno¬ 
manian of Normandy and the upper part of the English Green¬ 
sand, such as would naturally strike anyone who knew the English 
Chalk and Greensand only from published descriptions. These 
points are— 
1. The glauconite character of the beds. 
2. The occurrence of frequent layers of cherty concretions. 
3. The presence of Pecten asper and other fossils common in the 
Warminster Greensand. 
The following remarks on these points are taken from our 
joint paper previously referred to: — 
“ (1) It is a mistake to suppose that the material of the ‘ craie 
glauconicuse ’ [of Havre] resembles that of our Greensand. The 
