228 



LITS COQUILLIEES. 



[Ch. XVI 



Lower Calcaire grossier, or Glauconie grossiere, B. 5. — The lower part 

 of the calcaire grossier, -which often contains much green earth, is char- 

 acterized at Auvers, near Pontoise, to the north of Paris, and still more 

 in the environs of Compiegne, by the abundance of nummulites, con- 

 sisting chiefly of N. laevigata, N scabra, and N Lamarcki, which con- 

 stitute a large proportion of some of the stony strata, though these same 

 foraminifera are wanting in beds of similar age in the immediate environs 

 of Paris. 



Soissonnais Sands or Lits coquilliers, B. 6. — Below the preceding 

 formation, shelly sands are seen, of considerable thickness, especially at 

 Ouisse-Lamotte, near Compiegne, and other localities in the Soissonnais, 

 about fifty miles N. E. of Paris, from which about 300 species of shells 

 have been obtained, many of them common to the Calcaire grossier and 

 the Bracklesham beds of England, and many peculiar. The Nummulites 

 planulata is very abundant, and the most characteristic shell is the 

 Nerita conoidea, Lam., a fossil which has a very wide geographical 



Fig. 240. 



Nerita conoidea, Lam. 

 Syn. 2f. Schmidelliana, Chemnitz. 



range ; for, as M. D'Archiac remarks, it accompanies the nummulitic for- 

 mation from Europe to India, having been found in Cutch, near the 

 mouths of the Indus, associated with Nummulites scabra. No less than 

 thirty-three shells of this group are said to be identical with shells of the 

 London clay proper, yet, after visiting Cuisse-Lamotte and other localities 

 of the " Sables inferieures" of Archiac, I agree with Mr. Prestwich, that 

 the latter are probably newer than the London clay, and perhaps older 

 than the Bracklesham beds of England. The London clay seems to be 

 unrepresented in France, unless partially so, by these sands.* One of the 

 shells of the sandy beds of the Soissonnais is adduced by M. Deshayes as 



Fig. 241. 



Cardium porvlosum. Paris and London basins. 

 * D'Archiac. Bulletin, torn. x. ; and Prestwich, Geol. Quart. Journ. 1847, p. 371 



