208 ON THE LAND AND FRESH-WATER MOLLUSCA
Planorbis contortus, L. Ponds and ditches: Wanstead,
Barking Side, Eastham, &c., and in River Roding; very common.
Physa hypnorum, L. Ponds, meadow grips, and shore ditch,
Barking Side. After a heavy flood in the Roding Valley, I have
seen dead shells by the score of this sinistral species, with those of
Limnaea peregra, Planorbis vortex, and P. spirorbis.
Physa fontinalis, L. Ponds at Fern Hall and Whips Cross;
fairly common. The transparent sinistral shell of this species, clasped
by the digitated upturned lobes of the mantle, makes the form an
interesting study.
Limnaea peregra, Muller. Ponds and ditches ; everywhere
extremely common, and variable in size and shape.
Limnaea auricularia, L. Two shells from a ditch in a
meadow on St. Swithin's Farm.
Limnaea stagnalis, L. Forest ponds at Whips Cross, ponds
and ditches, Barking Side ; the Lake and Shoulder of Mutton pond,
Wanstead Park; but not plentiful.
Limnaea palustris, Muller. Pond at Carswell; ditches and
grips, St. Swithin's ; and Whips Cross Ponds ; not common.
Limnaea truncatula, Muller. Ponds and ditches, Carswell
and St. Swithin's ; fairly abundant.
Limnaea glabra, Muller. One shell from a ditch on St.
Swithin's Farm, Barking Side.
Ancylus fluviatilis, Mull. River Roding, on leaves of
water lily (Nuphar lutea); and the Lake, Wanstead Park; not
abundant.
Ancylus lacustris, L. River Roding, on water lily; rare.
Order PULMONIFERA.
Family ARIONIDAE.
Arion ater, L. Wanstead, and throughout the district; very
abundant.
Arion hortensis, Ferussac. Wanstead, and Barking Side; not
common.
Family LIMACIDAE.
Amalia marginata, Muller. In fields and hedges at
Barking Side, and in garden at Carswell; not at all plentiful.
Limax maximus, L. In gardens and fields, &c., throughout