List of non-marine molluscs of Montana  The non-marine mollusks of Montana — a part of the molluscan fauna of the state in the Northwestern United States. The non-marine mollusks of Montana consist of land snails and slugs as well as freshwater snails, freshwater mussels and freshwater clams. A number of species of non-marine molluscs are found in the wild in Montana. There at least 155 species of gastropods found in Montana. Some of these species are exotics (not native to Montana) and some species have been designated as "Species of Concern". There are at least 42 species of freshwater bivalves known in Montana. The Montana Department of Fish, Wildlife and Parks has identified a number of bivalve species as "Species of Concern". Freshwater gastropods in Montana include:  Bithyniidae  Thiaridae  Valvatidae  Hydrobiidae  Acroloxidae  Lymnaeidae  Physidae  Planorbidae  Land gastropods in Montana include:  Succineidae Arionidae  Megomphicidae  Vertiginidae  Pupillidae  Discidae Limacidae  Agriolimacidae  Oxychilidae  Gastrodontidae  Pristilomatidae  Vitrinidae  Euconulidae  Haplotrematidae  Oreohelicidae  Polygyridae  Cochlicopidae  Charopidae  Punctidae  Thysanophoridae Valloniidae  Freshwater bivalves in Montana include:  Margaritiferidae  Unionidae  Sphaeriidae