KENNARD & WOODWARD : HOLOCENE MOLLUSCA OF LONDON WALL, ETC. 181 
The species of mollusca obtained were :— 
Agriolimax agrestis (Linn.). Planorbis albus, Miill. 
Vitrea cellaria (Miill.). », glaber, Jeff. 
,, metida (Mill.). ,, nautileus (Linn.). 
Hygromia hispida (Linn.). 5, marginatus, Drap. 
Vallonia pulchella (Miill.). ,, vortex (Linn.). 
Helix aspersa, Mill. ,, sptrorbis, Mill. 
», nemoralis, Linn. ,, contortus (Linn. ). 
Cochlicopa lubrica (Mill.). Jontanus (1 ightf.). 
Succinea elegans, Risso. Bithy ynia tentaculata (Linn. ). 
Carychium minimum, Mill. », Leachit (Shepp.). 
Velletia lacustris (Linn.). Valvata piscinalis (Mill.). 
Limnea pereger (Miill.). ,, erestata, Mill. 
», palustris (Miull.). Spherium corneum, Linn. 
», stagnalis (Linn.). "4, lacustre, Mull. 
Physa fontinalis (Linn.). Pisidium pusillum, Gmel. 
5, Aypnorum (Linn.). ,, nitidum, Jenyns. 
Planorbis corneus (Linn.). ,, mielium, Held. 
Of these the most noteworthy are Planorbis glaber, P. fontanus, and 
Spherium lacustre. 
Planorbis glaber is extremely rare in Holocene beds, being known 
only from Westminster, Raine, Barry Docks, and from alluvial deposits 
near Edinburgh. It was not an abundant form at London Wall, but 
was far more prevalent than P. albus. 
P. fontanus is another rare form in Holocene beds, but it has been 
found at Raine, Crossness, Charlton, the Lea Valley, Westminster, 
and the Hampshire tufaceous beds. 
Spherium lacustre has hitherto been represented in a fossil state 
solely by specimens in the York Museum, said to come from the 
Pleistocene of Barnwell. It is a widely distributed form in these 
Islands at the present day, and is certainly not a modern introduction ; 
but since its habitat is usually muddy ponds or ditches, it is unlikely 
to be found in the stream deposits which form the vast majority of 
our fossiliferous Pleistocene and Holocene beds. 
In 1890 eleven species of shells were described! from a similar 
deposit at Moorfields, and the large size to which many of the examples 
attained was remarked upon. The examples from London Wall are 
equally noteworthy.  Succinea elegans attains a length of 18 mm., 
Physa hypnerum 14mm., and Limnea palustris 22 mm., whilst 
Planorbis corneus attains a breadth of 25°5mm., P. marginatus 16 mm., 
P. vortex 8mm., and P. fontanus 7-5 mm. Helix aspersa is not un- 
common, and occurs throughout the Roman layer. 
' B. B. Woodward, ‘‘ On the Pleistocene (non-Marine) Mollusca of the London 
District’? : Proc. Geol. Assoc., vol. xi, p. 339. 
