320 
ON THE OCCURRENCE OF WNERITINA GRATELOUPIANA, FER. 
(HITHERTO MISIDENTIFIED AS WN. FLUVIATILIS), IN THE 
PLEISTOCENE GRAVELS OF THE THAMES AT SWANSCOMB. 
By A. 8S. Kennarp and B. B. Woopwarp, F.L.S., etc. 
Read 13th March, 1903. 
In 1900 a new section was opened in the high terrace gravel of the 
Thames at Swanscomb, and yielded large numbers of mollusca as well 
as abundant remains of vertebrata. This was of great importance, 
since the horizon had hitherto afforded but very few bones or shells. 
The first account of this deposit was by the late Mr. H. Stopes,! 
whilst in 1901 we described the mollusca.? In these papers Weritina 
Aluviatilis (Linn.) was recorded as occurring there in great numbers, 
it being in fact the commonest form. We had, however, our doubts 
as to the correct determination, and a close examination of thousands 
of examples convinced us of our error in referring the Swanscomb 
Neritina to the existing English species. Through the kindness of 
Mr. H. Preston examples were submitted to Dr. O. Boettger, and he 
at once identified them as WV. Grateloupiana, Fer. ( =crenulata, Kiein), 
and stated that the form was represented in his collection from the 
Upper Miocene of Hider, near Dinkelscherben in Bavaria ; Pflummern, 
in Wirtemberg; and Neuberg-a.-Donau, in Bavaria; and from the 
Middle Miocene of Kosteg, Comitat Krass6 Szorényi, in Hungary. 
According to Sandberger,*® the species occurs in the Upper Miocene 
at Vermes near Delsberg, Berlingen um Untersee, Mammern, Rath 
near Weiach, Littenhaid near W yla, Schwammendingen, and Kipfnach, 
in Switzerland ; cat Engelswies near Mosskirch, and Dettighfen near 
Thiengen, in Baden ; at Deutschhof near Pflummern, Altheim near 
Ehingen, Hegebach, and Biberach, in Wiirtemberg; at Giinzburg, 
Hiiufelsburg, Reisensburg, Landestrost, Haider near Dinkelscherben, 
and Schwenditobel near Pfrungen, in Bavaria; at Hoflein, Hauskirchen, 
Feldsberg, and Brunn near Vienna, in Austria; at Radmanyest, in 
Hungary ; and at St. Agata near Tortona, in Piedmont: while from 
the Lower Miocene he records it from Mandillot and Mainot near Dax. 
The nearest living form is Weritina Danubialis, Milf. As we have 
already stated, it was the commonest shell at Swanscomb, occurring 
1 1900. H. Stopes, ‘‘On the discovery of Neritina fluviatilis with a Pleistocene 
fauna and worked flints in High Terrace Gravels of the Thames Valley” : 
Journ. Anthrop. Inst., vol. xxix (N.s., vol. ii), pp. 302-3. A second edition of 
the reprint, issued by the author in July, 1901, contains a fuller list of species 
found up to that date. 
2 A. S. Kennard & B. B. Woodward, ‘‘ The Post-Pliocene Non- Marine Mollusca of 
the South of England’’: Proc. Geol. Assoc., vol. xvii, pp. 238-9. 
3 ««Tand- und Stisswasser-Conchylien der Vorwelt.’’ 
