FOSSIL ESSEX MOLLUSCS
107
glacial. Indeed there is much to link the upper levels with the exposures
of gravel in the Botany Pit nearby in which the writer has found very large
concentrations of Levallois cores and flakes (unpublished to date). Levallois
techniques are relatively unknown in this country in the Hoxnian Inter-
glacial.
It is evident from the investigations so far that the sequence is of great
interest and that much further work will be required to be done in the area
before the relationship of the various components of the gravel spread at
Purfleet is known.
Acknowledgements
The very great assistance afforded by the late Mr C. P. Castell in
identifying and dating the Molluscan Fauna from specimens sent to him is
acknowledged with gratitude. Thanks are also due to the members of the
Hornchurch Historical Society whose assistance was greatly valued.
Finally thanks are afforded to Messrs P. and T. Allen who criticised the
manuscript.
TABLE 1
AQUATIC BIVALVES No. identified
Unio pictorum (L.) 9
Unio tumidus Philipsson 21
Corbicula fluminalis (Muller) 59
Sphaerium corneum (L.) 7
Pisidium amnicum (Muller) 87
Pisidium clessini Neumayr 9
Pisidium casertanum var. ponderosum Stelfox 15
Pisidium subtruncatum Malm 2
Pisidium supinum Schmidt 47
Pisidium henslowanum (Sheppard) 45
Pisidium nitidum Jenyns 9
Pisidium moitessierianum Paladilhe 21
AQUATIC GASTROPODS
Valvata cristata Muller 2
Valvata piscinalis (Muller) 4
Valvata antiqua Morris 42
Bithynia tentaculata (L.) 517
Bithynia tentaculata (L.)—opercula 127
Belgrandia marginata (Michaud) V.A.
Lymnaea palustris (Muller) 1
Ancylus fluviatilis Muller 28
Acroloxus lacrustris (L.) 36
LAND SNAILS
Succinea sp. 1
Cochlicopa lubrica (Muller) 1
Vallonia costata (Muller) 1
Clausilia sp. 1
Hygromia hispidia (L.) 1
Helicella itala (L.) 1
Helix nemoralis (L.) 2