Ch. XVI] 



FOSSILS OF THE BAETON CLAY. 



213 



1766, an account of the organic remains collected from these Barton ana 

 Hordwell cliffs, and his excellent figures of the shells then deposited in 

 the British Museum are justly admired by conchologists for their accuracy. 



SHELLS OF THE BARTON CLAY, HANTS. 



Certain foraminifera called Nummulites begin, when we study the 

 tertiary formations in a descending order, to make their first appearance 



Fig. 198. 



Fig. 199. 



Fig. 200. 



Fig. 201. 



Mitra seabra. Voluta ambigua. Typhis pttngens. Voluta athleta. Barton 



and Bracklesham. 



Fig. 202. 



Fig. 203. 



Fig. 204. 



Fig. 205. 



Terebellum. fast- Terebellum con- 

 forme. Barton volutum. 'Lava. 

 and Bracklesham. Seraphs convolu- 

 tum, Mont£ 



Cardita globosa. 



Orassatella sulcata. 



in these Barton beds. A small species called Numrmilites variolaria is 

 found both on the Hampshire coast and in beds of the same age in 

 Whitecliff Bay, in the Isle of "Wight. Several marine shells, such as 

 Corbula pisum, are common to the Barton beds and the Hempstead or 

 Upper Eocene series, and a still greater number, as before stated, are 

 common to the Headon series. 



Bagshot and Bracklesham beds, B. 5. — 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 of about the 

 same age as the Barton series. Although the Bagshot beds are usually 



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



