The Lenham Sandstones of Kent. 261 



In addition to these organisms the Lenham sandstones occasionally 

 exhibit impressions of the spines of Cidaris clavigera, Konig, and 

 remains of Inoceramus-shell associated with the sponge Cliona, all of 

 which belong to the Chalk (Senonian) formation, and are con- 

 sequently of derivative origin. No trace has been discovered in these 

 beds of any fossils which could possibly have been derived from 

 Eocene rocks. 



BiBLiOGHAPHr (1 857-1915). l 



The history of the Lenham deposits and their fauna was commenced 

 by the late Sir Joseph Prestwich in 1857, 2 when reporting the 

 discovery by W. Harris and Rupert Jones of certain "blocks of 

 gritty ferruginous sandstone, full of casts of shells", in some sand- 

 pipes in the Chalk at Lenham, eight miles east of Maidstone, which 

 they regarded as belonging to the basement-bed of the London Clay. 

 Prestwich was familiar with similar sandstones occurring at Paddles- 

 worth, near Folkestone, at a height of about 600 feet above sea-level, 

 and at Vigo Hill nearOtfordin Kent, mentioning likewise that they 

 were to be found in scattered fragments along the summit of the 

 North Downs, extending from near Folkestone to Dorking in Surrey; 

 but from the fossils he considered that the sandstones were of Lower 

 Crag age, on account of the presence of a Terelratula resembling 

 T. grandis, several species of Astarte, and a large Lutraria-like shell ; 

 this view being also shared by Searles Wood, who had examined the 

 fossil remains, and recognized the importance of the occurrence of a 

 Pyrula and an Emarginala as supporting that horizon. Prestwich 

 also noted that beds of similar structure were present on the hills 

 between Calais and Boulogne, at Cassel Hill near Dunkirk, and at 

 Louvain and Diest in Belgium, besides thinking it possible that such 

 sandstones were connected with the Carentan beds of Normandy. 



In the following year Prestwich 3 again returned to the subject, 

 aided by Searles Wood. He noticed that many of the species found 

 at Lenham were of southern origin, thus confirming his previous 

 ideas that the deposits were of Lower or Coralline Crag age. His 

 determinations of the shells included the following forms : — 



Scaphopoda. 

 Dentalium costata (?). 



Gastropoda. 



Emarginula reticulata (?). Natica. 



Nassa prismatica (?). Rissoa (?). 



Scalaria subulata (?). Phorus, related to Trochus cumularis, 



Pyrula. Brong. 



Trochus. 



1 The conchological determinations mentioned in the following memoirs are 

 those of the authors themselves, without any attempt at a rectification of the 

 nomenclature. 



2 "On some Fossilif erous Ironstone occurring on the North Downs ' ' : 

 Quart. Journ. Geol. Soc, vol. xiii, pp. 212, 213, 1857. 



3 " On the Age of some Sands and Iron- Sandstones on the North Downs " ; 

 with a Note on the Fossils, by S. V. Wood : Quart. Journ. Geol. Soc. , 

 vol. xiv, pp. 322-35, 1858. 



