|Various examples of Caenogastropoda|
|Subclass:|| Caenogastropoda |
Cox, 1960 
Caenogastropoda is a taxonomic subclass of molluscs in the class Gastropoda. It is a large diverse group which are mostly sea snails and other marine gastropod mollusks, but also includes some freshwater snails and some land snails. The subclass is the most diverse and ecologically successful of the gastropods. 
Caenogastropoda contains many families of shelled marine molluscs – including the periwinkles, cowries, wentletraps, moon snails, murexes, cone snails and turrids – and constitutes about 60% of all living gastropods. 
The Caenogastropoda exhibit torsion, and thus are included in what was previously called the Streptoneura (meaning twisted nerves), also known as Prosobranchia (meaning gills forward). Specifically, they are characterized by having only a single auricle in the heart and a single pair of gill leaflets, and are equivalent to the Monotocardia or Pectinibranchia of older authors.
The taxon Caenogastropoda was first established by Leslie Reginald Cox in 1960 as a superorder  but now sometimes it is retained as a clade. Based on optimal phylogenetic analysis, it is deemed monophyletic.  This Caenogastropoda combines the older taxa Mesogastropoda and Stenoglossa from the classification by Johannes Thiele  and is equivalent to the revised Monotocardia as defined by Mörch in 1865.
Caenogastropoda can be divided into two major groups, based on the anatomy of the radula:
Ponder & Lindberg, 1997 and others since (e.g. Vega et al., 2006;  Harzhauser, 2004;  and Pina, 2002.  ) show Caenogastropoda as a superorder, following the sense of Cox, 1960. More recently Bouchet & Rocroi, 2005 revised Caenogastropoda as a clade.
The following classification was laid out in the taxonomy of Bouchet & Rocroi (2005): 
Colgan et al. (2006)  provided further insight into the phylogeny of Caenogastropoda. 
Sorbeoconcha should include [Cerithioidea + Campaniloidea + all Hypsogastropoda (i.e. the remaining Caenogastropoda)], see definition in Ponder & Lindberg, 1997: 225, not only [Cerithioidea + Campaniloidea] as suggested by the indent pattern in Bouchet & Rocroi. Neotaenioglossa Haller, 1892 suggested in Ruud Bank’s draft for Fauna Europaea is not retained because it would need severe emendation to remove Pyramidellids, Cerithioids, etc. included in its original definition, and therefore would be too far from Haller's concept if it were to fit the concept of Sorbeoconcha. Although cladistically sound, the taxon Sorbeoconcha is skipped in the classification scheme because (1) ten years after its publication, the name still sounds unfamiliar to most and (2) it is not very helpful in the classification because it includes the bulk of Caenogastropoda (only keeping out small stem groups Abyssochrysidae, Provannidae, and the architaenioglossate taxa). This is not final, opinions are welcome. 
Neogastropoda is an order of sea snails, both freshwater and marine gastropod molluscs.
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.
Heterobranchia, the heterobranchs, is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.
Sorbeoconcha is a taxonomic clade of snails, i.e. gastropods, mainly marine species with gills and opercula, within the clade Caenogastropoda.
Hypsogastropoda is a clade containing marine gastropods within the clade Caenogastropoda.
Littorinimorpha is a large order of snails, gastropods, consisting primarily of sea snails, but also including some freshwater snails and land snails.
The Aciculidae are a family of minute land snails which have opercula. In other words, Aciculidae are terrestrial operculate gastropods. Even though Aciculidae are land snails, they live in rather wet conditions, among mosses and dead leaves and they have sometimes been described as "winkles come ashore".
The taxonomy of the Gastropoda as it was revised in 2005 by Philippe Bouchet and Jean-Pierre Rocroi is a system for the scientific classification of gastropod mollusks. The paper setting out this taxonomy was published in the journal Malacologia. The system encompasses both living and extinct groups, as well as some fossils whose classification as gastropods is uncertain.
The taxonomy of the Gastropoda, as revised by Winston Ponder and David R. Lindberg in 1997, is an older taxonomy of the class Gastropoda, the class of molluscs consisting of all snails and slugs. The full name of the work in which this taxonomy was published is Towards a phylogeny of gastropod molluscs: an analysis using morphological characters.
Apogastropoda was previously used as a major taxonomic grouping of sea snails, marine gastropod molluscs. This infraclass mostly consisted of marine limpets and operculate snails. At least 20,000 species were considered to exist within the two clades that were included, Heterobranchia and Caenogastropoda.
Vetigastropoda is a major taxonomic group of sea snails, marine gastropod mollusks that form a very ancient lineage. Taxonomically the Vetigastropoda are sometimes treated as an order, although they are treated as an unranked clade in Bouchet and Rocroi, 2005.
Neritimorpha is a taxonomic grouping, an unranked major clade of snails, gastropod mollusks. This grouping includes land snails, sea snails, slugs, some deepwater limpets, and also freshwater snails. Neritimorpha contains around 2,000 extant species. Some Neritimorphs are commonly kept as pets. This clade used to be known as the superorder Neritopsina.
The Cerithioidea is a superfamily of marine, brackish water and freshwater gastropod containing more than 200 genera. The Cerithoidea are included unassigned in the subclass Caenogastropoda. The original name of this superfamily was Cerithiacea, in keeping with common superfamily endings at the time.
Architaenioglossa is a taxonomic group of snails which have gills and often an operculum. They are primarily land and freshwater gastropod mollusks within the clade Caenogastropoda.
Pachychilidae, common name pachychilids, is a taxonomic family of freshwater snails, gastropod molluscs in the clade Sorbeoconcha.
Dialidae, common name dialids, is a family of sea snails, marine gastropod molluscs in the clade Sorbeoconcha.
Litiopidae, common name litiopids, is a family of small sea snails, marine gastropod molluscs in the clade Sorbeoconcha.
Plesiotrochidae is a family of sea snails, marine gastropod molluscs in the clade Sorbeoconcha. According to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005) the family Plesiotrochidae has no subfamilies.
This overview lists proposed changes in the taxonomy of gastropods at the family level and above since 2005, when the taxonomy of the Gastropoda by Bouchet & Rocroi (2005) was published. In other words, these are recent updates in the way various groups of snails and slugs are classified.
Obtortionidae is a family of sea snails, marine gastropod molluscs in the superfamily Cerithioidea, that is within the clade Cerithimorpha or in clade Sorbeoconcha.