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PROCEEDINGS OF THE GEOlOGICAl SOCIETY. [Feb. 8, 



their mode of occurrence. Sometimes we find a thick ferruginous 

 rock, the hedding-planes of which are covered with thin layers of 

 oysters ; at other times a hard blue-hearted calcareous rock, emitting 

 a fetid odour under the hammer, and almost whoUy made up of 

 oysters and other marine shells. The oyster-beds usually contain a 

 large quantity of carbonaceous matter, and in places, indeed, pass 

 into what might be called impure lignite. The thickest of them 

 measures about four feet, and it contains several interstratified bands 

 of clay, which, like the similar beds below, contain many small 

 oysters scattered through it. 



The fossils of these oyster-beds appear to be for the most part 

 marine. By far the most abundant are two species of oysters, one 

 plain, the other plicated. A careful comparison of a large series of 

 these convinces me that they are dwarfed forms of Eosoyyra sinuata 

 Sow., and £J. Boussingaultii, D'Orb. Almost all the shells found 

 in these beds appear to be stunted in their growth, probably from 

 having lived under unfavourable conditions. No specimens of 

 Ammonites have been obtained from these beds, and only one small 

 and doubtful example of a Vicarya. The following are the fossils 

 hitherto obtained from the oyster-beds of Punfield. 



Exogyra sinuata, Sow. (very abundant) 



Boussingaultii, U (^^^.(very abun- 

 dant). 



Pecten, sp. (very small). 



Cardium subhillanum, Leym. (rather 

 rare). 



Corbula striatula, Sow. (abundant). 

 Anomia laevigata, Sow. (abundant). 

 Modiola giffreana, Fict. et Eoux 

 (rare). 



Several small univalves. 

 Much carbonized wood. 



In the same part of the series as the oyster-beds there occurs a 

 bed of Sandstone containing Cyprides and casts of Cyrena. 



C. " The Marine Band of Punfield." This bed, though only 

 21 inches thick, is of the greatest interest, presenting us as it does 

 with a very considerable marine fauna, and thus furnishing the 

 means of correlating this portion of the Wealden with the series 

 of marine formations. It forms a well-marked feature in the cliiF 

 at Punfield Cove, dipping due N. at an angle of 65°. In its general 

 characters it is very similar to the oyster-beds above. The oysters 

 in this bed, which are of the same species as those in the oyster-beds 

 (^Exogyra sinuata and E. Boussingaultii), attain however to a 

 larger size, and approach more nearly to their normal forms than in 

 the latter beds. The specimens of Corbula striatula and Cardium 

 subhillanum likewise attain to larger dimensions. But besides the 

 shells which occur in the oyster-beds, we find in this band many which 

 are much more decidedly marine, including Ammonites Beshayesii, 

 several forms belonging to the new genus Vicarya, and species 

 of Trochus, Natica, Actceon, Actceonella, Orthostoma, Pholadomya, 

 &c. 



The upper part of the marine band consists of a hard laminated 

 micaceous sandstone, more or less calcareous, containing much 



