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

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of minute

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

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.php ...

.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). Whorls in nature File:Photograph and axial plane floral ...

s have an impressed suture. The

body whorl The body whorl is part of the morphology of the 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. In gastropods In gastropods, the b ...

is bluntly keeled at the periphery. There is a sculpture of dense spiral microscopic striae. The base of the shell is rounded. The umbilicus is narrow and deep, and it is surrounded by a callus funicle which expands anteriorly to join the simple lip in an angular lobe. The

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

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 ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

, Victoria, Australia, 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