This volume covers the mollusc families Moitessieriidae, Stenothyridae and Bythinellidae of the West Palaearctic that contain 23 genera. A total of 464 species have been depicted on 521 photo plates with nearly 1600 professional photos, most of them displayed for the first time. For the depictions, the author worked predominantly with syn-, holo-, para-, and topotypes where possible. Identifications with type-materials are important because formerly species have been identified regionally, i.e. all Bythinella from Crete are mentioned as B. cretensis in the literature but on Crete, there are three distinct species known so far. On the other hand, many type localities have been destroyed in the last decades and a dramatic decline and loss of mollusc diversity have been detected. Maybe many species listed in this volume are nowadays extinct. It is not possible to distinguish the genera of the Moitessieriidae and Hydrobiidae because there is a large overlap in shell shapes and penes morphology between these families, so the identifications keys for both families are displayed in both volumes 2 and 3, to make identification possible. The basis of the species considered in this book are the lists of the Fauna Europaea project, published by Ruud Bank (2004, 2011a, 2011b) as well as Bank & Neubert (2018) with additions of species which have been described after 2011 and Vinarski & Kantor (2018) for Russia. These checklists have been expanded by species living outside Europe. The borders of the West-Palaearctic are Iceland in the north, the Ural, along the Caspian Sea to Iran in the east, the Near East and Northern Africa to Portugal in the west. In addition, species names in doubt have been compared with WORMS (World Register of Marine Species).