288 



MIDDLE EOCENE, ENGLAND. 



[Ch. XVI. 



ance in these Barton beds. A small species called Nummulites 

 variolaria is found both on the Hampshire coast and in beds of the 

 same age in WhiteclirT Bay, in the Isle of Wight. Several marine 

 shells, such as Carbula pisum, are common to the Barton beds and the 

 Hempstead or Lower Miocene series, and a still greater number, as be- 

 fore stated, are common to the Headon series. 



MIDDLE EOCENE, ENGLAND. 



Bagshot and BracMesham beds, B. — The Bagshot beds, consisting 

 chiefly of siliceous sand, occupy extensive tracts round Bagshot, in 

 Surrey, and in the New Forest, Hampshire. They may be separated 

 into three divisions, the upper and lower consisting of light yellow 

 sands, and the central of dark green sands and brown clays, the whole 

 reposing on the London clay proper.* The uppermost division is 

 probably very nearly related in age to the Barton series. Although 

 the Bagshot beds are usually devoid of fossils, they contain marine 

 shells in some places, among which Venericardia planicosta (see fig. 

 235) is abundant, with Turritella sulcifera and Nummulites laevigata 

 (see fig. 239, p. 289). 



Fig. 235. 



Venericardia planicosta, Lam. 

 Cardita planicosta, Deshayes. 



At BracMesham Bay, near Chichester, in Sussex, the characteristic 

 shells of this member of the Eocene series are best seen ; among 

 others, the huge Cerithium giganteum, so conspicuous in the calcaire 

 grossier of Paris, where, it is sometimes two feet in length. The 

 volutes and cowries of this formation, as well as the luniilites and 

 corals, seem to favor the idea of a warm climate having prevailed, 

 which is borne out by the discovery of a serpent Palceopliis typhoeus 

 (see fig. 236), exceeding, according to Professor Owen, twenty feet 

 in length, and allied in its osteology to the Boa, Python, Coluber, 

 and Hydrus. The compressed form and diminutive size of certain 



* Prestwich, Quart. Geol. Journ., vol. iii. p. 386, 



