§46 M. Brongniart on the 



and of Krzeminiec in Volhinia. The chalk is there white 

 like that of Meudon ; it contains like it black flints, belem- 

 nites, (but apparently of a different species), cidarites tuI- 

 garls, plagiostoma spinosa of Sowerby, and probably other 

 organic remains, which the few specimens we possess do not 

 permit me to recognise. 



It appears that all the chalk of Poland presents the same 

 resemblance ; for Mr. Buckland, who observed it in place, 

 wrote me in 1820, that, " the chalk on which the castle of 

 Cracow stands, is precisely similar to that of Meudon, full 

 of echini and flints : it is perhaps a little harder. I have 

 not seen the plastic clay in contact, but I have observed 

 shells in the collections of Cracow, which resemble those 

 of the calcaire grossier, and sub-appennine mountains, which 

 were said to have been found at a short distance to the N.E. 

 of Cracow ; I have no doubt on the identity of the two 

 formations." 



§ V. Green Sand of the Pertc du Rhone near Belle- 

 garde. 



Two very different rocks are observed at this remarkable 

 place : the inferior is a compact, fine, grey, and yellowish 

 limestone, disposed in regular and nearly horizontal strata, 

 which at first sight shew no organic remains. De Saussure 

 observed this circumstance, and assures us that none were 

 ever found in it ; extensive and numerous cavities occur in 

 this compact limestone, through which the waters of the 

 Rhone are precipitated. 



Between these beds, and probably even beneath them, 

 raarl beds occur, as throughout the Jura, very different from 

 the limestone I have just mentioned, and which contain a 

 great quantity of shells. I am only acquainted with these 

 fossil shells from the statement of M. Deluc, and the speci- 

 mens he has sent me ; but the species of these fossils, and 

 the nature of the accompanying stone, establish the greatest 

 resemblance between these marl beds and those interposed 

 in the midst of the Jura limestone. 



