102 THE POST-PLIOCENE NON-MARINE MOLLUSCA OF ESSEX.
error in identification. In the Journal of Conchology for 1892
(page 64) is a note "that Valvata piscinalis var. antiqua Sow. is now
considered to be practically the form named by Dr. Jeffreys var.
subcylindrica and as Sowerby has priority it has been adopted."
It is no doubt desirable to relegate to obscurity many of the
names given to the so-called "varieties" of our British shells,
but in this case two perfectly distinct forms have been con-
founded. Dr. Jeffreys expressly states that his form subcylindrica
has a flattened apex. A reference to the original figures of var.
antiqua (5) would at once have shown the author of the above
remark that in this variety there is a perfectly regular spire and
no trace of flattening. We have never seen living examples of
antiqua from the British Isles, though according to Dollfuss
(1884. Ann. Soc. R. Malacol. Belg. xix., Mem. pp. 33 note), it is
now living in the canals of Northern France. On the other
hand we have seen examples of var. subcylindrica from four or
five localities.
The shell figured by S. V. Wood, 1st Supp. Crag. Moll.,
Tab. III., fig. 21, as Potamides sp. from Grays, is without doubt
a derived specimen from the Eocene beds of the neighbourhood.
In the original notice of Unio littoralis as a British fossil (5) there
is an error in locality. The figure of the shell is labelled Grays,
while in the accompanying list it is only recorded from Erith,
and in the text no mention is made of Grays, so there can be
no doubt that it was not known from the latter place till a
subsequent date. The earlier geologists were rather careless
about exact localities, the formation being considered sufficient.
This may account for some examples of Unio tumidus at the
Natural History Museum being labelled Crayford. This species
has never been found at that place, and judging by the condition
of the shells themselves, Grays should be substituted for the
present incorrect locality.
WEST THURROCK.
There, in the pit belonging to the Tunnel Cement Works
Company, Mr. W. J. Lewis Abbott, F.G.S., found some shells
on loamy clay with sandy patches that rested on a series of
sands and gravels overlying the chalk and abutting against an
escarpment of the latter. The list is not large and the speci-
mens are in a very fragmentary condition, with the exception
of an abnormal example of Helicella itala. This specimen