A comparative study of the five living species of the genus Schilderia has been carried out, taking into account conchological, anatomical (radular) and ecological features, and shows the close relationships existent between the Mediterranean-Atlantic species (S. achatidea) and the W. Pacific ones (S. hirasei, S. teramachii, S. sakuraii, and, specially, S. langfordi). This fact, together with the actual longitudinal discontinuous geographical distribution, suggests the existence of a past geographic continuity, with the presence of connecting taxa through the Tethys sea. The study of the limited fossil record does not confirm or deny this hypothesis for Schilderia, or Zonarina, considered as its inmediate ancestor. Although the scarce palaeontological data demands caution in order to establish the center of origin of these genera and their 1ossible dispersa! directions, the known data seem to suggest a W. Tethyan origin and an eastward dispersal.