''Minolia pseudobscura'' is a fossil

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 ...

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 ...

Solariellidae.

Distribution

This fossil species occurs in

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

and

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 ...

. The small, solid shell has a depressed-conical shape. Its height attains 11 mm and its diameter also 11 mm. The shell contains seven

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 and a wide open umbilicus. The nucleus is smooth and rounded. The other whorls are tabulate with an almost horizontal surface and the lateral surface vertical and somewhat convex. 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. The thin peristome is continuous.Yokoyama Matajiro (1927), ''Fossil mollusca from Kaga'', Journal of the Faculty of Science, Imperial University of Tokyo; Section 2, vol. 2, pt. 4, pp. 165–182, pls. 47–49
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References

* Makiyama, J., 1959: ''Matajiro Yokoyama's Tertiary fossils from various localities in Japan. Part 3''. Palaeontological Society of Japan, Special Papers, no. 5, pp. 1–4, pls. 58–86 * Higo, S., Callomon, P. & Goto, Y. (1999). ''Catalogue and bibliography of the marine shell-bearing Mollusca of Japan''. Osaka. : Elle Scientific Publications. 749 pp.

External links

{{DEFAULTSORT:Minolia Pseudobscura pseudobscura Gastropods described in 1927