What is "atrina"

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.