''Crossea biconica'' 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 ...

micromollusc A micromollusc is a shelled mollusc which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine molluscs, although in addition, numerous species of land snails and freshwater molluscs also ...

, a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine current power * Marine debris * Marine energy * Marine habitats * Mari ...

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 ...

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

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 ...

Conradiidae Conradiidae is a taxonomic family (created in 1987 by Golikov & Starobogatov) of very small sea snails, marine gastropod molluscs or micromolluscs. These genera were previously included in the polyphyletic family Skeneidae. They belong within th ...

.Bouchet, P. (2012). ''Crossea biconica'' Hedley, 1902. Accessed through:

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scien ...

at http://www.marinespecies.org/aphia.php?p=taxdetails&id=596655 on 2012-09-01

Description

(Original description by

Charles Hedley Charles Hedley (27 February 1862 – 14 September 1926) was a naturalist, specifically a malacologist. He was born in Britain, but he spent most of his life in Australia. He was the winner of the 1925 Clarke Medal. Early life Hedley was born ...

) The height of the shell attains 1.7 mm, its diameter 1.6 mm. The minute but solid, white shell has a biconical shape. Its base is greatly produced, the periphery keeled. 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 are somewhat turreted.

Sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

: The first and second whorls are smooth, the third comparatively coarsely cancellated, the fourth contains dense fine spiral cords crossed by fainter growth lines which tend to bead the interstices. The base is two-thirds of the total height. The wide and deep

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 bordered by a conspicuous ridge, and has an elevated funicle winding within. The oblique

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, channelled by the umbilical ridge, and with a gutter at the termination of the funicle. A heavy outstanding varix occurs a short distance behind the aperture. The small size, produced base, and wide umbilicus are characters which distinguish this from other Australian members of the genus.Hedley Charles (1902) Studies on Australian Mollusca. Part VI; Proceedings of the Linnean Society of New South Wales vol. 27 (1902)
/ref>

Distribution

This marine species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Australia. It is found off the

Northern Territory The Northern Territory (abbreviated as NT; known formally as the Northern Territory of Australia and informally as the Territory) is an states and territories of Australia, Australian internal territory in the central and central-northern regi ...

and

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

References

* Hedley, C. 1902. ''Studies on Australian Mollusca. Part VI.'' Proceedings of the Linnean Society of New South Wales 27: 7-29 * Cotton, B.C. 1959. ''South Australian Mollusca. Archaeogastropoda''. Handbook of the Flora and Fauna of South Australia. Adelaide : South Australian Government Printer 449 pp.

External links

World Register of Marine Species
{{Taxonbar, from=Q5188539 biconica Gastropods described in 1902