lization events have occurred during the Paleozoic or Mesozoic. Gastropods are especially unique due to several fully terrestrial and epifaunal lineages that evolved during the Cenozoic. Some members of rissooidean families Truncatellidae, Assimineidae, and Pomatiopsidae are considered to have colonized to land during the Cenozoic. Most truncatellid and assimineid snails amphibiously live in intertidal and supratidal zones from brackish water to pelagic areas. Terrestrial lineages likely evolved from such ancestors. The rissooidean gastropod family Pomatiopsidae is one of the few groups that have evolved fully terrestrial taxa during the late Cenozoic in the Japanese Archipelago only. Shifts from aquatic to terrestrial life occurred at least twice within two Japanese endemic lineages in Japanese Pomatiopsidae and it started in the Late Miocene. About one-third of gastropod species are terrestrial. In terrestrial habitats they are subjected to daily and seasonal variation in temperature and water availability. Their success in colonizing different habitats is due to physiological, behavioral, and morphological adaptations to water availability, as well as ionic and thermal balance. They are adapted to most of the habitats on Earth. The shell of a snail is constructed of calcium carbonate, but even in acidic soils one can find various species of shell-less slugs. Land-snails, such as Xerocrassa seetzeni and Sphincterochila boissieri, also live in des