(Gmelin, 1790)
Description:
Shell ovate to slightly subtriangular, with a maximum length of 26 mm. Valve exteriors are finely ribbed and have concentric growth lines. The colour varies from dark bluish to a variety of shades of grey and brown. Sulcation of the anterior commissure occurs only in specimens more than about 16 mm long. Shell without punctae. The pedicle foramen is elongated and the ventral umbo is produced as a curved beak.
Internal:
No brachial loop. The lophophore is spirolophous, supported by short flattened crura. The two spirals projecting dorsally (H. psittacea internal); (H. psittacea internal photo).
Habitat:
It has been collected at depths from 15 to 1100 metres.
Distribution:
It has a cold-water circum-polar distribution; found in the North Sea around the Shetlands and Orkneys.