Stylommatophora is an order[3] of air-breathing land snails and slugs, terrestrialpulmonategastropodmolluscs. This taxon includes most land snails and slugs. Stylommatophorans lack an operculum, but some close their shell apertures with temporary "operculum" (epiphragm) made of calcified mucus. They have two pairs of retractile tentacles, the upper pair of which bears eyes on the tentacle tips. All stylommatophorans are hermaphrodites.
The two strong synapomorphies of Stylommatophora are a long pedal gland placed beneath a membrane and two pairs of retractile tentacles.[4]
Stylommatophora are known from the Cretaceous period up to the present day.[5] A molecular clock estimate puts the origin of the crown group also to the Cretaceous.[6]
^Solem A. (1978). Classification of the land Mollusca. In: Fretter V. & Peake J. (eds). Pulmonates, Vol. 2A. London, Academic Press, 49–97.
^Sutcharit C., Naggs F., Wade C. M., Fontanilla I. & Panha S. (2010). "The new family Diapheridae, a new species of Diaphera Albers from Thailand, and the position of the Diapheridae within a molecular phylogeny of the Streptaxoidea (Pulmonata: Stylommatophora)". Zoological Journal of the Linnean Society160: 1-16. doi:10.1111/j.1096-3642.2009.00598.x.