Mollusks do not seem to be common on bomb-sites, and the only records known to me are those of Lt.-Col. Bensley (London Nat, for 1951, pp. 83-4).
My own rather casual searches on many Liverpool bomb-sites from 1946 onwards only yielded mollusca on two sites which may be worth noting. The first site was quite small, at the corner of Hanover St. and Seel St., near Central Station. There were many plants; eighteen species of flowering plants and two ferns were recognised on my one visit (11.10.1957). No garden escapes were present. Woodlice, centipedes, spiders, and harvestmen (apparently Liobunum sp.) were all fairly frequent, and a small colony of Oxychilus cellarius (Ktill.) included both adult and young examples.
The second site was much larger, a much trampled area between Islington and Daulby St.. Only six species of flowering plants were seen 17.10.1961), but there was a large colony of Limax flavus L. under old flagstones and lumps of tarmac, together with two specimens of Milax sowerbii (Fer.). Both are probably relics of the old houses and gardens of the area.
All three species are probably survivors of the blitz and not recent immigrants.
N. F. McMillan