This list of the non-marine molluscs of Ireland comprises 169 species of non-marine molluscs that have been recorded as part of the fauna of Ireland. Ireland is an island in the northeastern Atlantic. It consists of the Republic of Ireland, also known simply as Ireland (or in the Irish language Éire), and Northern Ireland, which is part of the United Kingdom. Included in the list are terrestrial gastropods (land snails and slugs) and freshwater and brackish water gastropods and bivalves (mussels and clams). Molluscs that are fully adapted to live in the sea are not included here, except for one marine pulmonate snail that breathes air. Some species of gastropods listed (e.g. Peringia ulvae) live in habitats that are intermediate between freshwater and saltwater. Others live in habitats that are intermediate between land and saltwater. Both of these kinds of species are often also included in marine faunal lists. In addition to the species that live naturally outdoors in Ireland, there are at least 2 aquatic gastropod species which live only in artificially-heated indoor environments such as aquaria in greenhouses. These are known as "hothouse aliens", and in this list they are not counted as part of the total fauna. The mollusc fauna of the island of Ireland has not been as thoroughly researched as that of the island of Great Britain, and therefore it is possible that some uncommon and local species (whether native or introduced) may, as yet, have been overlooked. Even so, it seems that the non-marine molluscan fauna of Ireland is a smaller fauna than that of Great Britain. The following table shows a summary of species numbers. It is not always easy to define which species are aquatic and which are terrestrial, as some species such as Galba truncatula are virtually amphibious. It also can be difficult to determine which species are introduced, as some introductions are quite ancient, for example from the Paleolithic. Those species that do not have a shell usually do not leave an archaeological or fossil record, and therefore it is especially difficult to determine whether they are native or introduced. Conservation Species protected by EU Habitats Directive include: Geomalacus maculosus (annex II and IV), Vertigo angustior, Vertigo geyeri, Vertigo moulinsiana (annex II) and Margaritifera margaritifera (annex II and V). Two species have been protected by the Wildlife Act of 1976 since 1990: Geomalacus maculosus and Margaritifera margaritifera. They were added