150 Origin of the British Flora. 
POPULUS CANESCENS, Sm. 
Interglacial :— : 
Grays, Essex ; some leaves collected by Prestwich 
suggest this species, though they may belong to P. tremula, 
The specimens have suffered from long keeping. 
POPULUS TREMULA, L. 
Neolithic :-— 
Caerwys, Flintshire, in calcareous tufa. 
Recorded from Klinge bei Cottbus, in Prussia (Carl 
Weber); from Honerdingen, in Hanover (Carl Weber); 
also from the Birch, Pine, Oak, and Spruce Zones in 
Sweden (Gunnar Andersson). 
EMPETRUM NIGRUM, L. 
Neolithic :— 
Close y Garey, Isle of Man (beds B and C). 
Late Glacial :— 
Hailes, near Edinburgh (lower bed); Dronachy, Fife ; 
Corstorphine, near Edinburgh (lower bed); Crianlarich 
Perthshire ; Ballaugh, Isle of Man. 
Interglacial :— 
Airdrie, Lanark. 
Also recorded from Honerdingen, in Hanover, asso- 
ciated with Platanus, Juglans, Nagas, &c. (Carl Weber). 
CERATOPHYLLUM DEMERSUM, L. 
Neolithic (?) :— 
Casewick, Lincolnshire. 
Late Glacial :— 
Hoxne, Suffolk (bed C). 
