98 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



From this list it appears that of the total 171 French species at 

 Bracklesham, 10 seem peculiar to the Lits coquilliers, 12 to the Sahles 

 moyens, and 5 to beds higher or lower even than these*. The re- 

 maining 148 species embrace a very large proportion of the charac- 

 teristic forms of the Calcaire grossier. Although, considering the 

 magnitude of the Calcaire grossier fauna, this direct numerical rela- 

 tionship is not very strong, yet it is far closer than with any other 

 member of the French series. If, further, we look at the respective 

 deposits upon independent grounds, and apply, as I did in my last 

 paper, the test of actual progression to each within its own area, we 

 shall find that the relative position of each deposit is maintained in 

 a way which corroborates the synchronism suggested by a certain ex- 

 tent of community in the organic remains. Thus if we take 100 

 species of the Bracklesham Sands and Calcaire grossier respectively 

 we shall obtain the following results, showing the agreement existing 

 in the relation which these formations relatively hold with the other 

 deposits above and beneath them in the two countries : — 



English area. 



Per centage 

 range of 



Bracklesham 

 species. 



French area. 



Per centage 



range of 

 Calcaire gros- 

 sier species. 



Barton Clav 



30t 



100 



r unfossili- 

 \ ferous. 



15 



6 



Sables moyens 



35 



Bracklesham Sands 



Calcaire grossier 



100 



Lower Bagshot Sands 



Lits coquilliers andGlau- 

 conie moyenne 



IVantiuff ... 





London Clay 



29 



Woolwich and Reading series... 



Sables de Bracheux ... 



5 



A large portion of the testaceous fossils common to this period in 

 the two countries are amongst the most abundant and typical forms, 

 as will be readily seen by reference to the foregoing list, p. 93. 



On these grounds I consider we may fairly confirm the contem- 

 poraneity, in mass, of the Bracklesham Sands with the Calcaire gros- 

 sier, and it only now remains to see with which portion of the Cal- 

 caire grossier these sands are most closely alhed, and to search into 

 the causes of these differences to which allusion has been made. 

 To do this we must examine each division of the Calcaire grossier, 

 and so study its organic remains and structure as to ascertain how 

 far and where they harmonize with those of the Bracklesham Sands, 

 and what indications they afford of those different conditions which 

 prevail in this country. 



§ 2. The Calcaire Grossier — its divisions, and their organic remains 

 compared with those of Bracklesham. The relative conditions 

 under which these deposits were formed. 



The French geologists now generally divide the Calcaire grossier 

 into four subdivisions, which pass one into another, but present 



* These 27 species embrace some very characteristic forms of the several de- 

 posits. There are 42 peculiar to the Calcaire grossier. See list, 

 t The addition of the Bramshaw species would raise this proportion. 



