''Cirsonella carinata'', common name the ridged false-top-shell, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of small

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 ...

, a 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 ...

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 ...

Skeneidae The Skeneidae are a speciose family of minute to small marine gastropod molluscs in the superfamily Trochoidea.Bouchet, P.; Gofas, S. (2013). Skeneidae. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.ph ...

.Marshall, B. (2013). Cirsonella carinata (Hedley, 1903). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=720338 on 2013-10-02

Description

The height of the shell attains 1.7 mm, its diameter 1.8 mm. The minute, smooth and glossy, cream-colored shell has a turbinate shape. The four

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 have an impressed suture. The

body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk ...

is bluntly keeled at the periphery. There is a sculpture of dense spiral microscopic striae. The base of the shell is rounded. The

umbilicus Umbilicus may refer to: *The navel or belly button *Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy *Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants *Umbilicus ...

is narrow and deep, and it is surrounded by a callus funicle which expands anteriorly to join the simple

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

in an angular lobe. 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 subcircular. Hedley, C. 1903. Scientific results of the trawling expedition of H.M.C.S. "Thetis" off the coast of New South Wales in February and March, 1898, pt. 6. Memoirs of the Australian Museum 4(1): 326–402
(described as ''Crossea carinata'')

Distribution

This marine species occurs off

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

Victoria Victoria most commonly refers to: * Queen Victoria (1819–1901), Queen of the United Kingdom and Empress of India * Victoria (state), a state of Australia * Victoria, British Columbia, Canada, a provincial capital * Victoria, Seychelles, the capi ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, at depths between 73 m and 200 m.

References

* Cotton, B.C. 1959. ''South Australian Mollusca. Archaeogastropoda''. Handbook of the Flora and Fauna of South Australia. Adelaide : South Australian Government Printer 449 pp * Iredale, T. & McMichael, D.F. 1962. ''A reference list of the marine Mollusca of New South Wales''. Memoirs of the Australian Museum 11: 1–109

External links

* {{DEFAULTSORT:Cirsonella Carinata carinata Gastropods described in 1903