OF ILFORD, ESSEX.
215
distribution of the British Post-Glacial Mammals,"3 mentioned
that this species and Eulota fruticum occurred at Ilford. Thinking
that it was possible that examples might be in the Jeffreys
Collection now (alas!) in Washington, we wrote to Mr. W. H.
Dall, who kindly informed us that there are no specimens in that
collection. The species is of course now extinct in this country,
and is only known fossil from Barnwell, Copford, and Clacton.
By far the most interesting specimen in Mr. Hinton's
collection is a single example of Limnea glabra. At the present
time it is a widely distributed, though local, form in these
islands, but it has hitherto been unknown and unrecorded
(unfortunately we have had painful experience that the two
terms are not always synonymous) either from the Pleistocene
or Holocene. It was, of course, unlikely that so widespread a
form could be a recent introduction, and this example enables us
to fill up a gap in the geological record.
All the examples we have seen of Corbicula fluminalis from
the Cauliflower Pit are immature, thus differing from the fine
examples found at Uphall.
Vitrea nitidula is an interesting addition to the Ilford fauna.
Though an abundant form at the present time, and common in
many Holocene beds, it is only known from the Pleistocene of
Barnwell, N.E. London, and Copford.
An example of the dwarfed form of Limnaea palustris, which
occurs in the Pleistocene of Harwich and Crayford, is in Mr.
Hinton's collection.
Mr. Johnston and Mr. White have recorded Sphaerium
maenanum, Kobelt, from Uphall. This form is in our opinion not
entitled to rank as a distinct species, but should be considered a
variety of Sphaerium corneum (Linn.), which is well known to all
conchologists as a polymorphic form, and it is possible to arrange
a gradating series from typical corneum to typical maenanum. We
would take this opportunity of thanking Mr. Hinton, Mr.
Johnson, and Mr. White, whose continuous work in the field has
been the means of greatly extending our knowledge of the
Pleistocene Non-Marine Mollusca.
3 Quart. Jour. Geol. Soc. vol. xxv., p. 103.