''Minolia pseudobscura'' is a fossil

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), ...

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 ...

Solariellidae.

Distribution

This fossil species occurs in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

and

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 ...

. 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). In nature File:Photograph and axial plane floral diagra ...

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, 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. The thin

peristome Peristome (from the Greek language, Greek ''peri'', meaning 'around' or 'about', and ''stoma'', 'mouth') is an anatomical feature that surrounds an opening to an organ or structure. Some plants, fungi, and shelled gastropods have peristomes. In mo ...

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