216 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



almost preclude us from hoping to find in them a fauna equally 

 abundant with that of the presumed synchronous series in France. 

 In the neighbourhood of London, where however estuarine condi- 

 tions prevail, the organic remains have been the object of earher and 

 more continuous research, and the Usts of these fossils are therefore 

 fuller and more satisfactory. 



In East Kent the number of marine species hitherto determined 

 from the Woolwich and Reading series amounts to fifteen. Limited 

 as is this fauna, it is very characteristic. Seven of the species are 

 likewise found in the lower sands of the neighbourhood of Beauvais 

 and of Rheims. These are the, — 



Cardium Plurasteadiense, Sow. (C. Cytherea Bellovacina, Desk. 



semigranulosum, Sow. of Graves.) Pectunculus terebratularis, Lam. {P. 



Corbula Regulbiensis, Mor. (C. Ion- brevirostris, & P. Plumsteadiensis, 



girostris, Desh. of Graves.) Sow.) 



Cucullaea crassatina, Lam. Teredina personata, Desh. 

 Cyprina Scutellaria, Desh. 



Of the other eight species, four (the Cardium Laytoni, Glycimeris 

 Rutupiensis, Sanguinolaria Edwardsii^ and Ampullaria subdepressa) 

 being new, and but recently described, have not yet been compared 

 with foreign specimens ; the Corbula Arnouldii ? occurs in the 

 lignites near Rheims ; the Teredo antenautcB may probably prove a 

 variety of the Teredina personata ; so that there are only two of 

 the older-known described species (the Thracia oblata and Cyprina 

 Morrisii) which have not yet been quoted in the French lists*. 



The seven species common to the two countries are precisely those 

 which are amongst the most characteristic fossils of the lower sands 

 of the Beauvais district, as they are of the Woolwich Sands of 

 East Kent. 



As before mentioned, the Woolwich and Reading beds present, in 

 their western area, an evidently continuous and unbroken series of 

 like sands and mottled clays from top to bottom ; but, as they range 

 by the neighbourhood of London, the fluviatile and freshwater clays 

 and lignites of Woolmch and Lewisham, set in in the midst of this 

 series, dividing it into three divisions. The lower one consists of 

 sands and pebbles ; the middle, of clays ; whilst in the upper one, 

 sands again predominate. As they trend eastward, the central divi- 

 sion thins out, and the upper and lower beds of sand blend and form 

 an indivisible series. The lower division, with marine shells, of 

 East Kent contains in West Kent a few sestuarine shells only ; 

 whereas the upper division, in the neighbourhood of Woolwich and 

 Bromley, has a rich fluviatile and sestuarine fauna, with also some 

 marine shells ; but as the fresh and brackish water fossils are of 

 identical species in the three divisions, I consider them, notwith- 

 standing the occasional and exceptional presence of marine forms, as 

 forming only one group. Taking now, therefore, the Woolwich 

 series of West Kent in its entirety, we will first examine how far its 



* Both, however, have been figured since the publication of M. Graves's and 

 M. Melleville's lists. 



