80
NOTE ON THE OCCURRENCE OF FRESH-
WATER MOLLUSCA IN A WATER-MAIN
AT POPLAR.
By A. S. KENNARD and B. B. WOODWARD, F.L.S., F.G.S.
[Read April 4th, 1903.]
IT has long been known that fresh water mollusca are able to
accommodate themselves to the artificial conditions of
underground water-pipes, but hitherto only three species,
Dreissensia polymorpha (Pall.), Neritina fluviatilis (Linn.),
and a Limnaea have been recorded.1 Of these the first-named has
been found in London, Manchester, and Birmingham, while the
two latter occurred in London. Recently Dr. Frank Corner,F.G.S.,
forwarded to us some material which had been obtained from a
disused iron water-main in Poplar. On examining it we were
able to identify no less than eleven species of mollusca: —
Ancylus fluviatilis. Mull.
Velletia lacustris (Linn.)
Limnea pereger (Mull.)
Planorbis crista (Linn.)
„ albus, Mull.
Neritina fluviatilis (Linn.)
Bithynia tentaculata (Linn.)
,, leachii (Shepp).
Dreissensia polymorpha (Pall.)
Sphaerium corneum (Linn.)
Pisidium subtruncatum, Malm.
From the numbers there can be no doubt that these species
had thoroughly established themselves in such apparently
uncongenial surroundings. The most abundant form was
Dreissensia polymorpha, but none of the examples attained to a
large size, 27 mm. being the length of the largest valve, but this
is apparently owing to the crowded manner in which they lived.
The next most abundant form was Planorbis crista (=nautileus),
which occurred of all ages, and was well-developed, some
examples measuring 3 mm. in diameter. P. albus also was by no
means dwarfed, the largest specimen attaining a diameter of
5 mm.
1 Jeffreys (J. G.) British Conchology (1862). Vol. 1, p. 48).
Standen (R.), Naturalist, 1887, pp. 159-160.
Macgillivray (J.), Zoologist, 1852. Vol. x., p. 3,420.