100 THE ESSEX NATURALIST
occurs sporadically from the Norwich Crag to the Upper
Pleistocene, is a consistent indicator of interglacial conditions.
It would appear likely that C. fluminalis and P. clessini
became extinct in the Thames river system by the latter part
of the Last Interglacial, neither species being yet known from
warm faunas belonging to the Upper Floodplain Terrace aggra-
dation. This suggests, as does the geological evidence and that
afforded by the Mammalia, that the Ilford deposits are not later
than the earlier part of the Last Interglacial, though it would
be unwise to place too much reliance on negative evidence of
this character.
In conclusion, it may be noted that there appears to be
little support for Kennard's contention that the sands and
brickearths north of the London Road (Cauliflower Pit, etc.)
differ significantly in age from those at Uphall (Kennard,
1916, p. 255). The most recent account of the Ilford shell
fauna is that given by Kennard and Woodward in 1900. But
revision is much needed, and the important Antonio Brady
collection of non-marine Mollusca from the early sections in
the Uphall Brickyard, later acquired by Kennard and now in
the British Museum (Natural History), has never been
described.
BIBLIOGRAPHY
The following is a list of papers which contain original
observations on the Ilford deposits or their fauna. No refer-
ences are however included to the standard monographs on
British Pleistocene Mammalia by Dawkins and Sandford
(1866-72), Leith Adams (1877-81) and Reynolds (1902-39), all
of which contain descriptions of Ilford specimens.
1823 Buckland, W. Reliquiae Diluvianae. 4to. London.
[Early reference to fossil Mammalia at Ilford, p. 175].
1838 Morrris, J. On the deposits containing carnivora and
other Mammalia in the Valley of the Thames. Mag.
Nat. Hist. 2 (N.S.), 539-548.
1847 Cotton, B. P. On the Pliocene deposits of the Valley
of the Thames at Ilford. Ann. Mag. Nat. Hist. 20,
164-169.