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

A. rigida (Lightfoot, 1786) is found on the southeast coast of North America and in the West Indies.

[1] 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 within the genus Atrina include:[1] This bivalve-related article is a stub.