88 THE POST-PLIOCENE NON-MARINE MOLLUSCA OF ESSEX.
been founded on several collections, which we have quite
failed to trace, and a comparison in the table at the end, of
the records which are listed on authority, will at once show how
great, and perhaps irreparable, has been the loss. The method
of procedure adopted, when all attempts to trace a collection have
ended in failure, has been to reject all records which were in-
herently improbable, and to list the remainder on the authority
of the recorder.
To Dr. Henry Woodward, F.R.S., we are greatly
indebted for affording us every aid in working at the examples
under his charge in the Natural History Museum; and
Mr. E. T. Newton, F.R.S., and Mr. H. A. Allen, F.G.S., of the
Museum of Practical Geology, as well as Mr. James Reeve,
Curator of the Norwich Museum, have been equally courteous. To
these gentlemen we would here return our most cordial thanks,
and would include with them Mr. W. J. L. Abbott and Mr.
F. C. J. Spurrell for permission to examine the specimens in
their possession. We would also express our gratitude to Mr.
W. M. Webb, F.L.S., for kindly examining the examples pre-
served in the Essex Field Club's Museum, and also for furnishing
the list of the species now existing in the county, besides
much other assistance noted in the paper. Our special thanks
are due to Dr. Frank Corner for placing at our disposal the
whole of his collection (a selection from which has been made
and is now on view at the Natural History Museum), as well as
for many other acts of kindness.
In the Essex Naturalist and in the Geological Survey
Memoirs mention is often made of the occurrence of shells
in Post-pliocence beds as at Yeldham, Audley End, Newport,
Little Chesterford, Bartlow, and Marks Tey. The collection
of these fossils is pre-eminently the work of local geologists,
and we would urge members of the Essex Field Club to
carefully preserve any specimens which may be obtained from
sections exposed in drainage or other works. Much good
work has already been accomplished in this direction by
members of the Club, especially by Mr. R. Miller Christy,
F.L.S., Mr. R. W. Christy, Mr. J. French, and Mr. W. M.
Webb, F.L.S. Our hope is that this paper will act as au incen-
tive to further work, and that more careful and extended research
in the future will be the result.
In the table at the end will be found a complete summary
concerning this distribution of the various species. In the first