Obsolete gastropod taxa

Pulmonata or pulmonates is an informal group (previously an order, and before that, a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includes many land and freshwater families, and several marine families.

thumb|Shells from a variety of prosobranch gastropods, from Ernst Haeckel's [[Artforms of Nature, 1904.]]

Opisthobranchs () is a now informal name for a large and diverse group of specialized complex gastropods which used to be united in the subclass Opisthobranchia. That taxon is no longer considered to represent a monophyletic grouping.

Pteropoda (common name pteropods, from Ancient Greek πτερόν (pterón), meaning "wing", and πούς (poús), meaning "foot") are specialized free-swimming pelagic sea snails and sea slugs, marine opisthobranch gastropods. Most live in the top 10 m of the ocean and are less than 1 cm long. The monophyly of Pteropoda is the subject of a lengthy debate; they have even been considered as paraphyletic with respect to cephalopods. Current consensus, guided by molecular studies, leans towards interpreting the group as monophyletic.

Basommatophora was a term that was previously used as a taxonomic informal group, a group of snails within the informal group Pulmonata, the air-breathing slugs and snails. According to the taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), whenever monophyly has not been tested, or where a traditional taxon of gastropods has now been discovered to be paraphyletic or polyphyletic, the term "group" or "informal group" was used.

Archaeogastropoda (also known as Aspidobranchia) was a taxonomic order of snails used in older classifications of gastropods, i.e. snails and slugs. Archeogastropoda are primarily marine prosobranch gastropod mollusks, mainly herbivores, typically having two gills and a double-chambered heart, with the eggs and sperm discharged directly into the water, excepting terrestrial species. They were traditionally regarded as a relatively primitive group.

thumb|right|alt=a red shelled marine snail with a white and black spotted foot|Conus geographus (a marine snail) Orthogastropoda was a major taxonomic grouping of snails and slugs, an extremely large subclass within the huge class Gastropoda according to the older taxonomy of the Gastropoda (Ponder & Lindberg, 1997).

thumb|Aporrhais pespelecani Mesogastropoda was for many years a traditional taxonomic group of snails, an order. The order was composed mostly of sea snails, but it also included some land snails and freshwater snails, all of which were prosobranch gastropod mollusks.

Eogastropoda was a previously used taxonomic category of snails or gastropods, a subclass which was erected by Ponder and Lindberg in 1997. It was one of two great divisions (subclasses) of the class Gastropoda, the snails. The other subclass of gastropods was the Orthogastropoda.

Notaspidea, also known as the sidegill slugs, is an artificial grouping of sea slugs which is now split into two unrelated groups, the Umbraculida and the Pleurobranchomorpha.

The Neotaenioglossa is a taxonomic name for a large group of mostly sea snails. The name was originally created by Haller in 1882. Ponder and Warén (1988), and Marquet (1997), assigned this name to the superorder Caenogastropoda. ITIS considers the order Neotaenioglossa to be a synonym of Cerithioidea Férussac, 1819 .

Heterostropha was a previously used taxonomic category, an order of sea snails, within the superorder Heterobranchia. In the most current gastropod taxonomy, that of Bouchet & Rocroi, this taxon is no longer in use.

Orthurethra is a clade of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Stylommatophora.

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 Acavoidea are a taxonomic superfamily of air-breathing land snails and slugs, terrestrial pulmonate gastropod mollusks in the informal group Sigmurethra.

Apogastropoda is a clade of gastropods uniting the highly diverse Caenogastropoda and Heterobranchia. Most caenogastropods are sea snails, whereas heterobranchs include not only sea snails but most species of sea slug, land snail, and land slug.

Fusus is a genus of small to large sea snails, marine gastropod molluscs in the family Fasciolariidae, the spindle snails and tulip snails.

Metarminoidea is a provisional taxonomic superfamily of colourful sea slugs, aeolid nudibranchs, marine opisthobranch gastropod molluscs in the clade Nudibranchia.

The Euomphalina comprise a major suborder of mainly Paleozoic archaeogastropods, shells of which are hyperstrophic to depressed orthostrophic, commonly with an angulation at the outer upper whorl surface thought to be coincident with the exhalent channel; shell wall thick, outer layer calcitic, inner layers aragonitic but not nacreous; operculum calcareous and heavy. Their range is from the Upper Cambrian to the Triassic, and possibly as high as the Upper Cretaceous.

Elasmognatha is a taxonomic grouping, a clade, of air-breathing land snails and slugs, terrestrial pulmonate gastropod molluscs.