280 M. Brongniart on the Calcareo-trappean 



of the calcaire grossier in the environs of Paris, only because 

 the limestone is there more abundant than the green earth, 

 whilst in the Vicentin the trappean rock predominates. 



We cannot follow the author through all the developements 

 he gives these objects of comparison, nor his citations of the 

 nataralists who have more or less approached this result ; 

 but we cannot avoid citing Mr. Buckland with him, as hav- 

 ing, during the tour he made in Italy nearly at the same 

 time as M. Brongniart, conceived a similar opinion as to the 

 epoch of formation of these rocks. 



In a second memoir,* which M. Brongniart has not yet 

 read to the Academy, he refers some other places he has 

 observed or become acquainted with to the same formation, 

 i'. e. to the lower marine formation or calcaire grossier of the 

 environs of Paris ; such are among others : 



1st. The high hill of the Superga, on the E. of Turin, 

 principally composed of calcareous marl and calcareo-ser- 

 pentine brecciola, containing shells for the most part aiiala- 

 gous to the species of Bordeaux, Chaumont, and some other 

 places which decidedly belong to the lower formations of 

 the upper sediment (tertiary) rocks. 



2dly. The summit of the Diablerets chain, above Bex, in 

 the Valais. This rock differs from that of Paris, by its 

 position, by its elevation of at least 2400. metres [7,874 

 feet] above the level of the sea, by the black colour and 

 hardness of its calcareous and bituminous beds, but wliich 

 may apparently be referred to this formation from the nature 

 of the organic remains it contains, which are cerithia, am- 

 pullariae, a cardium, very near the ciliare of M. Brocchi, if 

 it is not the same, the melania costellata, or a very near 

 species, a hemicardium, which is analogous to the retusum 

 or medium, &c. + 



* This forms the seconJ part of the author's recently published me- 

 jnoirs on the Vicentin rocks. (Trans.) 



+ We must not confound this with another rock, -svliich appears to 

 resemble it in its colour, position, &c. ; but which essentially differs from 

 il in its shells; and which forms part of ttx? mountains nf Sales, Varens, 

 &c, on the S.W. of the Eiut. The author, in a memoir inserted in 



