Prof. Coquand on the Cretaceous Strata of England and France. 401 



referred the phenomena in question to " segregation" they were all 

 shown to be easily capable of explanation on well-known chemical 

 principles, and to be due to the action of atmospheric water finding 

 access to the rock by its joints and fissures. 



The paper concluded with a sketch of what was inferred to be the 

 history of the rock from its accumulation to the present time, and 

 some remarks on the varied and important effects of water when 

 acting under different conditions on rocks. 



2. " On the Occurrence of Eemains of Pterygotus and Eurypterus 

 in the Upper Silurian Bocks in Herefordshire." By the Rev. P. B. 

 Brodie, M.A., F.G.S. 



In this paper the author described the occurrence of numerous 

 specimens of Crustacea, chiefly belonging to the genera Eurypterus 

 and Pterygotus, in beds of Upper Silurian age, probably the " passage 

 beds," in the "VVoolhope district and near Ludlow. 



March 24th, 1869.— Sir Philip de M. Grey Egerton, Bart., M.P., 

 F.E.S., in the Chair. 



The following communications were read : — 



1. "On the Cretaceous Strata of England and the North of France, 

 compared with those of the "West, South-west, and South of France, 

 and the North of Africa." By Professor Henri Coquand, of Mar- 

 seilles. 



In this paper the author indicated that the agreement between the 

 Cretaceous strata of England and the North of France, as far as the 

 Basin of Paris, is such that the same classification may be applied to 

 the whole, but that in advancing to the west and south new beds 

 make their appearance. This is also the case in Algeria, the palse- 

 ontological differences between the Cretaceous rocks of that country 

 and those of the Anglo -Parisian basin being so great as to lead at 

 first sight to the impression that they belong to two different 

 formations. The author arrived at the following classification and 

 nomenclature of the divisions of the Cretaceous rocks, the palseonto- 

 logical characters and geographical range of which were described 

 in the paper : — 



I. Upper Cretaceous. 



A. Red Lancus trine Sandstone of Vitrolles ( =Garumnien of Leymerie). 



B. Dordonien. 



C. Campanien (= Upper Chalk). 



D. Santonien (= Superior Lower Chalk). 



E. Coniacien (Sandstone). 



II. Middle Cretaceous. 



F. Provencien. 



G. Mornasien. 

 H. Angoumien. 



I. Ligerian (= Inferior Lower Chalk). 



J. Carentonien. 



K. Gardonien. 



L. Rothomagien (= Upper Greensand and Chalk- marl). 



M. Gault. 



