THE POST-PLIOCENE NON-MARINE MOLLUSCA OF ESSEX. 107
Elliotti fruticum is only known from Ilford, the record for
Copford being an error for which in all probability the printer
was responsible. Elsewhere in England the only known localities
are Barnwell, where it was fairly common, and Stutton, in
Suffolk, where a single example was found by Mr. S. V. Wood.
When the streams on which these several localities occur are
traced to their sources it will be seen that the Roding, the Stour,
and the Granta (which joins the Cam just above Cambridge) all
rise within a short distance of each other in North-west Essex ;
so it seems a not unnatural inference that this species may have
formerly had its head-quarters there. In which case Essex
Naturalists should look for it in the deposits of the Chelmer and
Blackwater, which likewise rise in that area, especially since Mr.
W. H. Dalton (Essex Naturalist, vol. iii, 1889, p. 10) men-
tions some Helices resembling this species being found at a
point seven miles north-west of Colchester.
The former presence of some species which at the present
time are more northern in their distribution should be noted :
such as Acanthinula lamellata, Pupa anglica, and Vitrea excavata.
The first-named must formerly have been very abundant, since
it occurs in profusion at Copford, and it has also been found in
four other localities. Why these species should have died out in
the county is a problem to which we can suggest no answer.
With two exceptions, all the existing species of Vitrea have
been found ; the missing ones being V. alliaria, so abundant at
Ightham, and the so-called glabra. What the correct name for
this latter species really should be is still a matter of dispute.
Succinea oblonga is only known with certainty to occur in the
Chelmsford Brick-earth and Clacton. At the present time it is
unknown in the home counties, though it formerly occurred at
Battersea, and examples from that locality are now in the
Natural History Museum.
Acicula lineata is another species which was formerly
extremely abundant. Though it has not yet been recorded in
a living state from the county, this may arise from the fact that
it is a very local species and difficult to find.
The diminution in area of distribution of Pomatias elegans is
very marked, as it is now only living in one locality. A similar
state of things occurs in Suffolk, where, in the eastern part of
that county, it has become extinct.