THE POST-PLIOCENE NON-MARINE MOLLUSCA OF ESSEX. 99
specimens under his care. There is also a small series in the
Prestwich Collection at the Natural History Museum, for a
knowledge of which we must thank Mr. R. Bullen Newton.
From these we have been able to verify forty-six species. Of
the two described as new by Mr. Sowerby, Helix conoidea is
certainly Hygromia hispida.
The identification of Planorbis helicoides is not quite so certain.
No figure is given as with H. conoidea, and we have only the
description to guide us. Mr. A. Bell has suggested P. glaber,
but this is not likely, as P. Levis (a synonym for P. glaber) is
recorded. But from the statement that it resembles P. lineatus,
but without the septa, we are of opinion that P. fontanus is the
shell meant, and examples of this species are in the Geological
Society's Museum. The following have been omitted, being far
too uncertain :—Helix umbilicata [=Pyramidula rupestris], Helix
[=Hygromia] rufescens, Achatina [=Caecilianella] acicula, and Helix
[=Vitrea] alliaria. Clausilia biplicata is an error in identification
for Clausilia rolphii, and Helix virgata for Helicella caperata. Palu-
dina minuta is now Paludestrina marginata, Paludina thermalis is
Paludestrina ventrosa, Paludina impura is Bythinia tentaculata,
Clausilia bidens is Clausilia laminata, Pupa palustris is Vertigo anti-
vertigo, and Pupa cylindrica is Vertigo minutissima.
There still remain, however, fifteen species to be accounted
for, and these we have listed on the authority of the first recorder
for what they may be worth. In the 2nd Supplement to the
Crag Mollusca, p. 69, Tab. I, fig. 4, a and b (19), are the descrip-
tion and figures of two specimens of Paludina found at Clacton
by the Rev. O. Fisher, for which Mr. S. V. Wood proposed the
name of P. clactonensis, but pointed out that a shell from the
diluvium at Templehof, near Berlin, called P. diluviana, Kunth
(Zeitschrift. Deutsch. Geol. Geschellschaft, Berlin, 1865, Tab. 7,
fig. 8), very much resembles these specimens, and may be
identical. (These are the shells referred to by Mr. S. V.
Wood, junr., as Paludina lenta, see ante). Another example has
since been found by Mr. A. Bell. Professor C. L. F. Sandberger,
however, is of opinion that the two forms are quite distinct, and
that the nearest allies to the Clacton shell are Vivipara lenzi,
moisisovicsi and brusiuai, Neumayr, from the Congeria beds of
Sclavonia. The type specimens are in the Woodwardian
Museum at Cambridge, and we regret that lack of opportunity
has up to the present prevented us from examining them.