A taxonomic revision of the Bulimulidae of Sonora, Mexico is undertaken. The existing species are redescribed and their ranges given. Four new species are described and one species synonymized on the basis of anatomical and conchological characteristics. In addition a new genus, Drymaeus Albers, 1850, is recorded for the state and several species are reassigned from Rabdotus Albers, 1850 to Naesiotus Albers, 1850. The zoogeography of the Sonoran species and genera is also presented along with their relationships to congenerics in the rest of North America. It was determined that one of these genera Naesiotus has a North American-South American disjunct distribution and that both it and Rabdotus probably had Southern Hemisphere origins. The mechanisms of isolation and dispersal are discussed and a microplate tectonics model is presented to explain them. The Gondwanaland distribution of the subfamily is also described.