Diagnosis: Moderately sized, valves smooth, elongate ovate to subpentagonal in outline, biconvex; lateral commissure curved towards dorsal valve, anterior commissure rectimarginate to parasulcate. Beak low, erect; deltidial plates conjunct in adults as symphytium, exposed; foramen small, permesothyridid, beak ridges rounded; hinge teeth somewhat small relative to symphytium, bases not swollen, dental plates present, lamellar and straight; pedicle collar broad, sessile, impunctate. Cardinalia lamellar, inner and outer hinge plates well developed, crural bases not well-differentiated, inner hinge plates form short septalium (shortest medially, anterior border indented or flat) supported by median septum; inner socket ridges lightly inclined; cardinal process not differentiated (absent); median septum extending anteriorly about ¾ valve length; crura short, subparallel, crural processes short. Adult brachial loop diploform (campagiform); Lophophore plectolophous (lophophore and mantle finely spiculate). (Modified from Atkins 1960, Emig 2022).