JURASSIC OP THE PARIS BASIN. 



587 



portions of the Portland limestones, will belong to the Lower 

 Portlandian. 



In bringing this Part I. to a close, I must not omit to return my 

 thanks to those who have assisted me ; especially to M. de Lapparent, 

 who enabled me to study the literature of the subject in Paris, and 

 who showed me the true Portlandian fossils from the Pays de Bray ; 

 to Prof. Hebert, who gave me many valuable indications of the best 

 localities to visit, without which my difficulties would have been 

 greatly increased ; to M. Rigaux, who has on several occasions guided 

 me in the Boulonnais ; to MM. Cotteau and de Loriol, who have given 

 me copies of some of their writings for reference ; and, finally, to the 

 Government-Grant Committee of the Eoyal Society, to whose recom- 

 mendation I owe the means of carrying on these researches on the 

 Continent. 



EXPLANATION OF PLATE XXVI. 



Comparative diagram sections of Upper Jurassic Eocks, Paris Basin 

 and England. 



Discussion. 



The President stated that the correlations of the author went 

 far to complete our knowledge of the Upper Jurassic rocks in the 

 Anglo-Parisian Basin. 



Mr. Hudleston was able to confirm the author's views concerning 

 the correlation of the Upper Jurassic strata in parts of this country 

 with those of the Ardennes as regards the lowest beds in question. 

 The coincidence in the faunas of the beds in these widely separated 

 areas was very remarkable. He thought Mr. Blake's observations 

 tended to support the views of M. Hebert rather than those of 

 M. de Loriol with respect to the importance of the Coral Rag as a 

 formation. He did not agree with the separation of the so-called 

 "Pterocerian;" nor could he agree with the author in absorbing the 

 greater part of the Kimmeridge Clay into his "Bolonian." The 

 author's Bolonian was called by the French authors Lower Portlan- 

 dian, and was claimed by them as the normal or characteristic de- 

 posit ; while the Portlandian in the south of England, on a higher 

 horizon, was the less constant development, and therefore more 

 truly the episode. 



Tne Author, in reply to Mr. Hudleston, stated that the Astartian 

 of this country resembled that of Normandy rather than that of 

 the Boulonnais ; but he agreed with him as to the Pterocerian. He 

 thought that the calling of the Bolonian by the name of " Port- 

 landian " had been a continual source of error. 



