F1TT0N ON THE ATHERFIELD AND HYTHE SECTIONS. 187 



M. Roemer considers the " yellow (Neocomian) limestone " as in- 

 ferior to his Hils-conglomerate and Hils-clay, which, however, 

 contain, like our Atherfield strata, many of the characteristic 

 Neocomian fossils. 



§. The Neocomian of the Crimea was described in the Letters 

 of M. Dubois, published in 1837 in the Bulletin of the French 

 Geological Society * : the writer having been the first, as he 

 states, to discover an analogue of the Neufchatel Neocomian in 

 the Crimea, which presents fossil species so much alike in form that 

 it was impossible to distinguish them ; the general aspect of the 

 beds also being perfectly the same. The lower bed, however, 

 (which M. Dubois calls Neocomien in his section,) may well be a 

 calciferous expansion of the lowest beds at Atherfield. It is cha- 

 racterised by the Terebratula biplicata and Exogyra Couloni (which 

 Professor Edw. Forbes considers as identical with E. Icevigata 

 of Sowerby), two of the most characteristic shells of the lowest 

 limestone of Kent. Above this, and next in succession, are about 

 40 feet of schist, which may represent our gault ; and between this 

 and the " etage superieur de la craie," is a series like the Upper 

 Green Sand. 



Beyond the Caucasus another Neocomian deposit exists at Kou- 

 tais and at Kereite, with fossils including small Nerinaea and 

 Diceras like those of Mont Venteux, Grenoble, but accom- 

 panied by many other of the more usual Neocomian species. 



It is not surprising that a statement by a naturalist and traveller 

 of such authority as M. Dubois, should have fixed the attention 

 of the French Geologists, who had previously been occupied with 

 the Terrain Neocomien. Nor was it unnatural that M. Dubois 

 himself, in recurring to his native country, should have looked 

 no farther; even if he had been acquainted with the English 

 works concerning the beds below the Chalk, where he might have 

 found other evidence of a striking affinity to what he has described. 



§. On a general view of the strata beneath the Chalk as they 

 exist upon our own coast, it is evident, that, notwithstanding the 

 local variations, the Lower Green Sand has a definite and distinct 

 character ; extending throughout from the Wealden to the Gault, 

 and bounded naturally by those two groups, with their distinct 

 and peculiar fossils : and it is apparent, also, that there is no 

 natural connection between the Upper and the Lower Green Sand. 

 The distribution of the fossils in the lower sands is very un- 

 equal ; they are numerous at the lower part, rapidly diminish up- 

 wards, and (at present) seem to be nearly wanting at the top j ; the 

 same species, however, are carried through the whole, the upper 

 fossils being a selection, as it were, from those below. It is in- 



* Bulletin, vol. viii. p. 385—389. 



f Among the fossils of these beds near Folkstone, where phosphate of lime 

 occurs in detached masses, are the remains of an Astacus, a plicated Terebratula, 

 stem-like concretions of Siphonaria, and fragments of an oyster or Gryphcea. 

 (See Geol. Trans, vol. iv. pp. 117, 118.) 



