GEOLOGICAL EANGE 269 



resemble in many points the Liassic series, and also 

 parts of the Gault, in containing a large proportion 

 of planulate Crisfellcu-icE, which points to similarity 

 in the conditions of habitat. The Thanet beds also 

 contain many Eotalines and the beaded form of 

 Gristellaria (C. fragravici), which are later found in 

 the London Clay of London and Sheppey in some 

 abundance. 



The clays of the Woolwich and Beading series, 

 consisting as they do of estuarine muds with much 

 ferruginous material, have not yielded more than 

 a few starved species, mainly of Rotalines, which 

 the author has noticed in certain samples from 

 Dorsetshire. 



In the London Clay, both in the London and 

 Hampshire Basins, we find a rich and varied 

 foraminiferal fauna. This formation is now held 

 by some geologists to belong to the Middle rather 

 than the Lower Eocene period ; the presence and 

 distribution of the Nummulites and other Fora- 

 minifera in equivalent strata elsewhere, however, do 

 not bear out this assumption. The equivalent strata 

 to the London Clay in the Paris Basin are the 

 Ypresien beds, containing Nummulites plan id a fa. 



The Middle Eocene also embraces the Brackles- 

 ham Beds, w^hich in the South of England contain a 

 stratum with Ntinnii/i/ife.s hevigatns^ associated with 

 a smaller species, A^. .scahra ; N. variola via also 

 occurs in the upper part of this series. Besides 

 these Nummulites there are a few species of Bilo- 

 culina, Miliolina, and some Rotalines, as Discorhina 



