Sigmurethra is a taxonomic category of air-breathing land snails and slugs, terrestrial pulmonate gastropod molluscs. This is an informal group which includes most land snails and slugs. The two strong synapomorphies of Sigmurethra are a long pedal gland placed beneath a membrane and retractile tentacles. Several families in this group contain species of snails and slugs that create love darts. Sigmurethra are known from the Cretaceous to the Recent periods.

Taxonomy

2005 Taxonomy

In the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005, Sigmurethra is an "Informal Group", a subsection of the Stylommatophora. It consists of the following families:

limacoid clade

Informal group Sigmurethra continued

Two superfamilies belongs to clade Sigmurethra, but they are not in the limacoid clade. (Families that are exclusively fossil are indicated with a dagger †)

New families after 2005

2017 Taxonomy

After excluding groups not related, the informal group Sigmurethra becomes suborder Helicina, with the following nine infraorders and a collection of families with no superfamily：