96 THE POST-PLIOCENE NON-MARINE MOLLUSCA OF ESSEX.
is very evident from the above that the shell bed which has since
made Copford famous was not exposed at this time. During the
next five years, however, the bed was laid bare, for in 1843 Mr.
J. Brown listed thirty-eight names on the authority of Dr. S. P.
Woodward (8). In 1852 Mr. Brown issued another list (10)
containing sixty-four names, Mr. Pickering being this time
responsible for the identifications ; whilst four years later (11)
Mr. S. V. Wood recorded sixty-three species, and figured Heli-
cella incarnata, Mull., from this locality. He mentioned, however,
that the two or three examples which he considered to be this
species were not in good preservation, and that the determination
was doubtful. The last-published list was issued in 1880 by the
Geological Survey (21), and added nothing except errors. It is
a matter of congratulation that Mr. Brown's original specimens
from which all the lists were compiled are now at the Natural
History Museum, and that consequently the work of checking
has been comparatively easy, though it should be mentioned that
through the generosity of Mr. Brown examples are to be found
in several museums and many private collections. The following
species have been excluded, no specimens being forthcoming :—
Limax carinatus, Vitrea alliaria, Helix [=Hygromia] fusca, Helix
[=Eulota] fruticum, Bulimus acutus, [=Helicella barbara], Achatina
[=Caecilianella] acicula (originally given with a query), Vertigo
minutissima, Limnaea [=Amphipeplea] glutinosa, Bythinia ventricosa
[=leachii], Anodonta cygnea, Corbicula fluminalis, Sphaerium rivicola,
Pisidium amnicum, and Helix [=Helicella] incarnata. Clausilia
plicatula is a synonym for C. rolphii, and Helix depilata, II. con-
cinna, and H. plebeia are only varieties of Hygromia hispida.. Mr.
Brown has recorded Helix hortensis, and examples so labelled are
at the Natural History Museum. As every malacologist is
aware, there is sometimes a difficulty with recent examples in
stating definitely whether a shell belongs to this species or to
Helix nemoralis, and in fossil examples where the coloration is
nearly always destroyed the difficulties are greatly increased.
We are, however, of opinion that in this case the identification
is correct.
So full are the original lists that there are only six species
to add, viz. : — Vitrea excavata, Helicella caperata, Vertigo moulinsiana,
Ancylus fluviatilis, Planorbis fontanus, and Paludestrina marginata.
There has always been considerable difference of opinion as to
the exact age of the Copford beds, and unfortunately the evidence
from the mollusca is rather contradictory. Pyramidula ruderata