Alvania obeliscus is an extinct species of minute sea snail, a marine gastropod mollusc or micromollusk in the family Rissoidae.[1]
| Alvania obeliscus | |
|---|---|
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| Shell of Alvania obeliscus (holotype) | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | Littorinimorpha |
| Superfamily: | Rissooidea |
| Family: | Rissoidae |
| Genus: | Alvania |
| Species: | †A. obeliscus
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| Binomial name | |
| †Alvania obeliscus Harmer, 1920
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Description
editThe length of the shell is 4 mm (0.16 in), and its diameter is 0.3 mm (0.012 in).
(Original description) The small shell is conical. It contains about 7 whorls, nearly flat. The shell is ornamented by strong longitudinal ribs, 15 or 16 on the body whorl, and by well-marked spiral ridges, especially conspicuous near the base. The suture is distinct but not deep. The spire is somewhat elongate, regularly diminishing upwards. The aperture is ovate, compressed and angulated above and rounded below. The outer lip is thin. [2]
Distribution
editFossils of this species were found in late Pliocene strata at St. Erth, Cornwall, Great Britain.
References
edit- ^ MolluscaBase eds. (2024). MolluscaBase. Alvania obeliscus Harmer, 1920 †. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=1027567 on 2024-02-07
- ^ Harmer F. W. (1920-1925). The Pliocene Mollusca of Great Britain, being supplementary to S.V. Wood's monograph of the Crag Mollusca. Vol. 2. Monographs of the Palaeontographical Society. 72(344): 485-652, pl. 45-52 (part 1, December 1920); 73(346): 653-704, pl. 53-56 (part 2, July 1921); 75(352): 705-856, pl. 57-64 (part 3, December 1923); 76(354): i-xiv, 857-900, pl. 65 (part 4, January 1925)
This article incorporates text from this source, which is in the public domain.
This article needs additional or more specific categories. (February 2024) |