Atrina

Atrina Temporal range:
Atrina zelandica
Fossil of Atrina pectinata
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Order:	Pterioida
Family:	Pinnidae
Genus:	Atrina Gray, 1847

Atrina is a cosmopolitan genus of bivalve molluscs belonging to the family Pinnidae.

A typical species is A. fragilis, found in British waters. A. rigida (Lightfoot, 1786) is found on the southeast coast of North America and in the West Indies. The type species is A. nigra (Dillwyn, 1817, originally P. nigra).

Atrina is considered to represent the more primitive form within the Pinnidae; however, both genera Pinna and Atrina are very ancient. The genus Atrina is represented within the fossil record from the Triassic period to the Quaternary period (age range: 242.0 to 0.0 million years ago). These fossils have been found all over the world.

Description

Molluscs within this genus are characterized by elongated, wedge-shaped shells, distinguished from the genus Pinna by the lack of any grooves in the nacreous lining of the shell, and by the central positioning of the adductor scar.

As with other pen shells (Pinnidae) they commonly stand point-first in the sea bottom in which they live, anchored by net of byssus threads.

Species

Species within the genus Barbatia include:

• Atrina affinis Sowerby 1821†
• Atrina argentea Conrad 1848†
• Atrina fragilis (Pennant, 1777) — fan mussel
• Atrina harrisii Dall 1898†
• Atrina jacksoniana Dall 1898†
• Atrina magellanica Ihering 1907†
• Atrina nigra (Dillwyn, 1817)
• Atrina pectinata †
• Atrina piscatoria Glenn 1904†
• Atrina rigida (Lightfoot, 1786) — stiff pen shell
• Atrina seminuda (Lamarck, 1819) — half-naked pen shell
• Atrina serrata (Sowerby, 1825) — saw-toothed pen shell
• Atrina stephensi Hanna 1926†
• Atrina talarensis Olsson 1928†
• Atrina vexillum (Born, 1778) — flag pen shell
• Atrina zelandica (Gray in Yate, 1835) — the horse mussel

References

• Packard, Earl; Jones, David L. (Sep 1965). "Cretaceous Pelecypods of the Genus Pinna from the West Coast of North America". Journal of Paleontology. 39 (1): 910–915.
• "Glossary". Man and Mollusc. Archived from the original on 18 January 2008. Retrieved 2008-01-30. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
• Mitchell, Patricia B. "American Stiff Pen Shell: Strength and Rigidity". Archived from the original on 20 December 2007. Retrieved 2008-01-31. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)

External links

• idscaro.net — images