TIIK KCCKNK SKKIKS f>L'7 



I. THE EOCENE SERIKS 



This series has lu-i-n divided intn a iniiul-r of stages for which 

 1 1 tl'rrent names are at present used in England, France, and Belgium, 

 as shown in the following table : 



Belgium. France. 



Barton Beds. Weminelian. Bartonian. 



Brackleshani Beds. Laekinian and \ r . 

 Bagshot Beds. Brussellian Beds./ 



London Clay. Sables de Mons. \ v 



Woolwich aud \ Argile de Flandres. / 



Readme Beds. / Upper \ T , Sparnaciai 



mi i L> i r Lanuenian. m\ 



Thanet-neds. Lower j Thanetian. 



A. LIFE OF THE PERIOD 



Eocene Life. The difference between the fauna of the Chalk 

 and that of the Eocene is very great indeed, for only one species, 

 and that is a Brachiopod (Terebratulina striata), seems to have 

 survived the change of conditions in Britain, and not only so, 

 but the general aspect of the Eocene fauna is quite different from 

 that of the Cretaceous. The great reptiles of the Secondary rocks 

 have disappeared, and with them the numerous Cephalopods which 

 are so characteristic of the Cretaceous System the Ammonites, 

 Turrilites, Baculites, Scaphites, Hamites, Belemnites, and many 

 other genera ; vanished also are the Hippurites, Eadiolites, and 

 Inocerami of the Chalk, most of the Cretaceous Echinoderms, and 

 all the deep-sea siliceous sponges (Ventriculites, Cephalites, Ploco- 

 spongia, etc.). 



In England the most abundant fossils are Gastropods and 

 Lumellibranchs, many of them belonging to genera which now 

 characterise much warmer seas than, those around our islands. 

 Brachiopods, Echinoderms, Corals, and Sponges are rare compared 

 with their numbers in Mesozoic deposits. 



The Eocene flora is marked by the abundance of Dicotyledons, 

 especially of genera which now occur in tropical and sub-tropical 

 regions. It should be mentioned, however, that many of the 

 genera which now make their appearance in Britain occur in the 

 higher Cretaceous deposits of the continent. The flora of the 

 Woolwich and Reading Beds, has a temperate aspect ; it includes 

 leaves like those of the poplar, plane, and hazel (Populus, Platanus, 

 and Corylus). The plants of the London Clay and Bagshot sand, 

 on the other hand, are those of a much warmer climate ; they 

 include leaves and fruits of the conifers Pinus and Sequoia, with 



