110 THE ESSEX NATURALIST
marginal region rich in plants. The mollusc suite, character-
istic of the Nazeing Stage, was as follows :
Valvata cristata (Muller)*
V. piscinalis (Muller)
Bithynia tentaculata (Linne)
Lymnaea truncatula (Muller) rare
L. peregra (Muller)
Planorbis planorbis (Linne) rare
P. laevis Alder
P. crista Linne
P. contortus (Linne) a fragment
Segmentina s.p.* rare
Acroloxus lacustris (Linne)* rare
Succinea sp. rare
Sphaerium corneum (Linne)
Pisidium sp. or spp.
A careful search was made for the land shells characteristic
of this stage but none was found in a considerable sample. If
present they were rare. It follows that the deposit is of purely
aquatic origin. Further, the presence of the three species
starred in the above list demonstrates that the material
includes some that is very late in the Nazeing Stage [Hayward,
1958].
A preliminary examination of fruits and seeds yielded a
number of species of which the most abundant were :
Ceratophyllum demersum Linne
Polygonum lapathifolium Linne
Potamogeton sp. or spp.
Two of these are new records for the Nazeing Stage. Neither
was recorded by Miss Allison from the type site and neither
has yet been found by the author from the corresponding
deposits at Deephams [Hayward, 1957a]. Of the Hornwort,.
Godwin [1956] records that the plant is somewhat common in
the middle part of the Post-Glacial period but is less frequent
in earlier and later deposits. The present record is therefore
important. Although P. lapathifolium was not found at
Nazeing, it is recorded from the Arctic Bed, and its presence
here is not surprising. Other species of the genus were found
at Nazeing.