The material for the present article is a collection of bivalves collected by V. D. Voznesensky in 1956 from the Middle Devonian deposits of the Karaganda region of Central Kazakhstan. The advantage of the collection is the large number of specimens and their good preservation.

Diagnosis. "Shell oval in shape, smooth or with concentric striae, with prosogyral beaks shifted forward. Along the hinge margin the teeth are continuous; in the posterior branch up to 50; in the anterior branch 7–15 larger teeth."