the Calcairc Grossier of Paris. 7 



whitish gray colour ; at others shining, almost translucent, and 

 of a more or less deep gray colour. The fossils which often 

 occur in it, in prodigious quantities, are white, calcareous and 

 well preserved, though thin and occasionally mixed with rolled 

 pebbles. 



This sandstone, the second above the chalk, and also the 

 chert with marine shells, which appears occasionally to re- 

 place it, sometimes occurs on or in the marine limestone as 

 at Triel, at Frene, at St. Jean les Deux Jumeaux, &c. Thev 

 sometimes seem entirely to replace the limestone, as in the 

 environs of Pontoise, at Essainville, and at Beauchamp near 

 Pierrelaie. 



Among the various shells contained in this sandstone, there 

 are many which appear to be of the same species as those found 

 at Grignon ; others differ a little. 



The following is a list of those shells which are the most 

 constantly found in this sandstone, and which, as it were cha- 

 racterize it by their presence : 



Calyptrceatrochiformis? . . . /Q"^rries of Beauchamp near 



Oliva Iaumo7itiana Pierrelaie, Triel. 



Ancilla canalifcra Triel. 



Voluta Harpula? Triel. 



Fiisus hidbijormis P Pierrelaie. 



Cerithium serratum Pierrelaie. 



tuherculosum Essainville. 



coronatum Pierrelaie. 



■ lajndum Pierrelaie. 



mutabile Pierrelaie. 



Ampidlaria acuta or spirata . . . Pierrelaie, Triel. 

 patula? (very small)! p. 



Nncula deltoidea? j- 1 lerrelaie. 



Cardium Lima? Pierrelaie, Triel. 



Venericardia imhricata Pierrelaie, Triel. 



Cytherea nitidula Triel. 



elegans? Triel, Pierrelaie. 



tellinaria Pierrelaie. 



Venus callosa ? Pierrelaie. 



Lucinu circinaria Essainville. 



saxorum. 



Two species of oyster still undetermined, one approachino- 

 Ostrea dcUoidea, and the other O. Cijmhida. 



It will be seen by this enumeration ; 1. that the species are 

 consideral)ly fewer than in the Grignon beds ; 2. that it is with 

 doubt that we have referred the greater part of these species 

 to the names given by M. Lamarck to those of Grignon. 



It 



