Alvania proavia

Alvania proavia
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Littorinimorpha
Superfamily:	Rissooidea
Family:	Rissoidae
Genus:	Alvania
Species:	†A. proavia
Binomial name
	†Alvania proavia; (Pilsbry & C. W. Johnson, 1917)
Synonyms
	† Rissoa (Alvania) proavita (subsequent incorrect spelling in Pilsbry, 1922: 384, 432); † Rissoa (Alvania) proavia Pilsbry & C. W. Johnson, 1917 (not a Rissoa);

Alvania proavia is an extinct species of minute sea snail, a marine gastropod mollusk or micromollusk in the family Rissoidae.^[1]

Description

The length of the shell attains 1.35 mm, its diameter 0.9 mm.

(Original description) The shell is imperforate, rather plump has a conical shape. The shell contains 4 whorls. The first 2½ whorls are smooth, convex, and form a somewhat acuminate summit. The following whorls have a latticed sculpture of rather narrow vertical ribs, which pass over the periphery but are obsolete over most of the base, crossed by spiral cords a little narrower than the ribs, and forming small nodes at the intersections. On the penultimate whorl there are three spiral cords, the upper one at the shoulder. On the body whorl there are six spiral cords, the second from above forming the periphery, the lower two smooth, the others passing over ribs. Some very minute spiral striae are visible in the intercostal spaces. The aperture is nearly circular,. The outer lip is strengthened by a strong varix. ^[2]

Distribution

Fossils have been found in Oligocene strata in the Dominican Republic

References

^ ^a ^b MolluscaBase eds. (2024). MolluscaBase. Alvania proavia (Pilsbry & C. W. Johnson, 1917) †. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=867175 on 2024-02-17
^ Pilsbry, H. A. & Johnson, C. W. (1917). New Mollusca of the Santo Domingan Oligocene. Proceedings of the Academy of Natural Sciences of Philadelphia. 69: 150-202 This article incorporates text from this source, which is in the public domain.

External links

Pilsbry, H. A. (1922). Revision of W. M. Gabb's Tertiary Mollusca of Santo Domingo. Proceedings of the Academy of Natural Sciences of Philadelphia. 73(2): 305-435, pls 16-4

[WoRMS-1] MolluscaBase eds. (2024). MolluscaBase. Alvania proavia (Pilsbry & C. W. Johnson, 1917) †. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=867175 on 2024-02-17

[2] Pilsbry, H. A. & Johnson, C. W. (1917). New Mollusca of the Santo Domingan Oligocene. Proceedings of the Academy of Natural Sciences of Philadelphia. 69: 150-202 This article incorporates text from this source, which is in the public domain.

[1]

[2]