Former Distribution of British Plants. 155 
POTAMOGETON NATANS, L. 
Neolithic :— 
Drope, Glamorgan. 
Late Glacial :— 
Ballaugh, Isle of Man (bed F). 
Interglacial :— 
West Wittering, Sussex. 
Also recorded from Klinge bei Cottbus, in Prussia ; 
Fahrenkrug in Holstein; Honerdingen, in Hanover (Carl 
Weber); and from the Birch, Pine, and Oak Zones in 
Sweden (Gunnar Andersson). 
POTAMOGETON RUFESCENS, Schrad. 
Late Glacial :— 
Twickenham, Middlesex ; Hoxne, Suffolk (bed C). 
Interglacial :-— 
Kilmaurs, Ayrshire (?) (Bennett). 
Also recorded from Honerdingen, in Hanover, asso- 
ciated with Platanus, Juglans, &c. (Carl Weber). 
POTAMOGETON HETEROPHYLLUS, Schreb. 
Neolithic :-— 
Drope, Glamorgan ; Hailes, near Edinburgh. 
Interglacial :— 
West Wittering, Sussex; Stone, Hampshire; South- 
elmham, Suffolk; Kilmaurs, Ayrshire (or P. Z2z72) 
(Bennett). 
Preglacial (Cromer Forest-bed) :— 
Abundant at most localities. 
