EOCENE STRATA IN ENGLAND, BELGIUM, AND FRANCE. 95 



The Glauconie Inferieure presents a marked analogy with the 

 "Woolwich Series, where we also have two beds of fossiliferous marine 

 sands divided by fluviatile carbonaceous clays and thin lignites. 

 The deposits are also alike in lithological character, that of Beauvais 

 consisting of white and light-green sands, often very pebbly, while 

 the carbonaceous clays form large lenticular masses in the middle of 

 the sands. There is also the like passage, on the same level, of 

 massive mottled clays into sands, and of sands into pebble-beds. 

 The fossils, which abound in some places and are absent in others, 

 are subject to similar variations, dependent upon variability of con- 

 ditions. Further this Glauconie Inferieure is replaced in the neigh- 

 bourhood of Paris, as the Woolwich Beds are in the neighbourhood 

 of Eeading, by red and mottled clays with a few beds of sand. 

 There is, however, this difference, that while the bulk of the fossils 

 in the Woolwich Series are in the sands above the fluviatile clays, 

 those in the Paris Basin at Beauvais are in the lower division of the 

 sands ; but, as at Woolwich, while there are a few species peculiar 

 to either bed, the greater part are common to the two. 



M. Graves enumerates 82 species* of Mollusca from the different 

 localities of these sands in the Oise ; but his list was made before 

 the publication of Deshayes's last work on the shells of the Paris 

 Basin, in which many rectifications were made, both in the names 

 of species and in their range. Consequ^ently the list requires con- 

 siderable revision. Deshayes, in that work, gives the names of all 

 the localities from which his specimens came. It is by taking all 

 his Bracheux specimens in combination with Graves's specifications 

 that the following list (p. 96) has been drawn up. It will serve as 

 a truer term of comparison than Graves's original lists. 



Here, out of 45 species, only 6 seem to be common to the Thanet 

 Sands, and 5 to the Lower Landenian, whereas there are 10 common 

 to the Woolwich Series. The numbers are not largef, but the 

 balance in favour of the higher horizon is clear ; and if the Lignite 

 species are to be included with them, as by M. Graves, the case in 

 favour of their synchronism becomes stronger. The absence in the 

 Thanet Sands and Lower Landenian of such characteristic forms as 

 the Cardita pectuncidaris and others, is an additional piece of evi- 

 dence that the two zones are distinct. In fact out of the 8 Bracheux 

 species selected by M. Graves as characteristic of the Bracheux 

 Sands, only 2 occur in the Thanet Sands and Lower Landenian. 



* This includes a number of freshwater species, some of which are given in 

 the second list, 



t If we had taken the beds of Abbecourt and Noailles, which belong to the 

 same zone as the Eracheux Sands, it would have increased the number of species, 

 but would not materially have altered the proportional distribution. 



