Dr. FiTTON on the Strata below the Chalk. 159 



Terebratula nuciformis. Upper member of the sands ; Pulborough Mount : Martin. 



rp depressa. Upper ferruginous member of the Lower green-sand ; Pulbo- 

 rough Mount: Martin MSS. 



y, (Another species — uncertain.) Same place : Martin. 



Thetis major. Lowest member of the sands; Pulborough: Martin. 



y minor. Bowyer's Common, and Lyss, near Petersfield : Mrs. Murchison. 



Parham : Mantell. Upper member of the sands ; Pulborough Mount: Martin. 



y (new). Stopham brick-yard. Martin MSS. 



Tn>om'a flte/brwi?s. 1 Bowyer's Common: Mrs. Murchison. Parham: Mantell. Stop- 



T davellata ?] ham : Martin. 



T dedalcea. Parham : Mantell. 



T spinosa. Pulborough : Martin, p. 33. 



Turbo rotundatus. Parham : Martin MSS. 



y . (Another species.) Near Pulborough : Martin, p. 31. 



Turritella granuluta. Parham, and Pulborough : Martin MSS. 



y . (Another species.) Near Pulborough : Martin MSS. 



Venus angulata. See Cyprina. 



V i'^^^-l Parham: Mantell. 



V ovalis. J 



V parva. See Cj/therea parva. 



y . (Casts of two other species.) Stopham : Martin MSS. 



Vermicularia concava. Parham-park, Parkmount-lane near Pulborough, Chiltington- 

 comraon. Martin, pp. 33 and 34. 



The Wealden. 



(76.) In adopting this general denomination, proposed by Mr. Martin, for 

 the formations below the green-sand, in the Wealds of Kent, Surrey, and 

 Sussex, I have extended its acceptation to the Purbeck strata also, which do 

 not occur within those counties ; because the whole group abounds in fossils 

 of the same character. And though the Purbeck strata consist principally of 

 limestone, which has many indications of lacustrine origin, they include, like 

 the upper members of the Wealden, distinct alternations of marine fossils 

 with those of freshwater : — one very thick bed especially, which consists al- 

 most entirely of oysters,* showing that the sea must have had access to the 

 waters from which they were deposited, Mr. Martin has ascertained that the 

 Wealden strata above the Purbeck, consist, throughout, of alternations of 

 sand, sand-rock, and grit, with clay and marl; so that the separation of the 

 Weald-clay from the Hastings sands, is in a great measure arbitrary. But as 

 in the only tracts where this group has yet been observed, the sands rise above 

 the valley of the clay, into a very prominent ridge, which forms a striking fea- 



* Webster: Geol. Trans., 2nd Series, Vol. U., p. 40. 



