Much of the wetland in Britain consists of very acid bogs, which have very few species indeed. Where there is more lime, though, our fens and marshes (including wet dune slacks) have some very characteristic species, some of which are amongst the most rare and threatened. There are big differences between, for example, lowland reedswamp and highland calcareous flushes; unlike the woodland fauna, it would very unusual to find most of these species in the same place. As with woodlands, a lot of other species are often found as well. Some of the species listed here occur in or near roadside ditches, or in wet patches in woods.
- Ashfordia granulata
- Carychium minimum - Also found in wet woodland.
- Deroceras laeve
- Euconulus cf. alderi
- Oxyloma elegans
- Succinea putris
- Vertigo substriata
- Zonitoides nitidus
- Quickella arenaria - Very rare, SW only
- Leiostyla anglica - Occasional; especially in west and north
- Oxyloma sarsii - Rare; SE only
- Succinea oblonga - Rare, especially on wet, bare mineral soils, not peaty fens.
- Vertigo angustior - Rare; found especially at the edges of wetlands, in transition zones.
- Vertigo antivertigo - Scarce
- Vertigo genesii - Very rare; north only
- Vertigo geyeri - Rare; generally on mineral soils / flushes
- Vertigo lilljeborgi - Rare
- Vertigo moulinsiana - Scarce