1847.] PRESTWICH ON THE BAGSHOT SANDS. 393 



however, in the thick and nearly imiform mass of loose siliceous sand, 

 are small ferruginous lumps and concretions, usually coated with the 

 sand in which they are imbedded. On carefully examining some of 

 these smaller concretions, which are about the size of a large marble 

 and nearly round, most of them, at many places on Frimley Ridge* 

 and Hartford Heath, show traces of organic structure, and prove to 

 be the casts of a small globose species of Cardium. In the larger 

 tabular lumps of rough iron sandstone, casts and impressions of shells 

 may also be occasionally detected. Weathered specimens are to be 

 found in the mounds of sand thrown up from the railway cutting at 

 Frimley Ridge. The following list is almost entirely from this loca- 

 lity. Owing to the very imperfect state of the specimens, the species 

 must be considered as determined with some doubt. 



Fossils of the Upper Bagshot Sands, 



Cardium. Ostrea flabellula, Lam. 



Cytherea ? Tellina scalaroides, Lam. 



Cypiicardia? Turritella (apparently the sulcifera or 

 Fiisus ? terebellata). 



Globulus patulus ?, Desk. (carinated and tuberculated spe- 



sigaretinus ?, Sow. cies). 



Infundibulum trochiforme, Sow. Trochus ? 



Melania costellata ?, Lam. Venericardia (species undescribed). 



Nummulites elegans, Sow. Voluta. 



And of fishes the remains of the 



Teeth of Lamna elegans. Coelorhynchus rectus. 



From the limited number of determinable species in this Kst, it 

 would be difficult to draw any well-founded opinion as to the precise 

 co-relation of these strata. Of the 8 or 9 species two have a range 

 through all the Eocene series ; of the remaining 7 three are common 

 to Bracklesham and Barton, one is chiefly confined to Barton, and 

 the remaining four are Bracklesham forms. That these sands belong 

 to one or the other of these two divisions I have but httle doubt. The 

 evidence, such as it is, would rather approximate them to the latter. 



It is possible that, taking as a base the green sands of the Brackle- 

 sham strata at White-Cliff Bay, where we have over them in ascend- 

 ing order a series of yellow and greenish sands and sandy brownish 

 and yellow clays, followed again by the yellow sands (Nos. 14 to 20, 

 section 6) on which repose the Freshwater series, we shall find, in 

 following the development of these upper beds westward from that 

 point, that they become more argillaceous and fossiliferous and in more 

 distinct stratification, ending in their most perfect development at Bar- 

 ton ; — that if, on the contrary, we trace them from White-Cliff Bay to 

 the northward and north-eastward we shall find them becoming more 

 arenaceous, the beds not so well defined, and the organic remains less 

 abundant ; and consequently, that a continuance of these lithological 

 changes, in proportion as the strata trend in this direction, might re- 

 sult in the nearly entirely arenaceous and unfossiliferous condition ex- 



* Between Chobham and Farnborough. 



