''Bembicium'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

s, marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Littorinidae The Littorinidae are a taxonomic family of over 200 species of sea snails, marine gastropod molluscs in the clade Littorinimorpha, commonly known as periwinkles and found worldwide. Names In English-speaking countries, gastropod molluscs from ...

, the winkles or periwinkles.

Description

(Described as ''Risella'') The depressed shell is trochiform, with flattened

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). In nature File:Photograph and axial plane floral diagra ...

s and a keeled periphery. The shell is not umbilicated. The

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

is rhomboidal, marked with brown inside the margin. The operculum is paucispiral. These shells are distinguished from ''

Trochus ''Trochus'' is a genus of medium-to large-sized, top-shaped sea snails with an operculum, of the family Trochidae, the top snails.Bouchet, P.; Gofas, S. (2010). Trochus Linnaeus, 1758. Accessed through: World Register of Marine Species at http:/ ...

'', which they resemble in form and sculpture, by their non-nacreous interior. The animal is distinguished by eyes on the tentacles instead of on peduncles, and by the absence of the lateral membranes of the foot.Tryon (1882) Structural and systematic conchology vol. I

Species

The following species are recognised in the genus ''Bembicium'': * †'' Bembicium altum'' * '' Bembicium auratum'' * '' Bembicium flavescens'' * †'' Bembicium hokianga'' * '' Bembicium melanostoma'' * '' Bembicium nanum'' * †'' Bembicium priscum'' * '' Bembicium vittatum''

References

{{Taxonbar, from=Q4885055 Littorinidae