Note:  Do not rely on this information. It is very old.

Gastrochaenidae

Gastrochaenidae, a family of Lamellibranohs' or bivalve molluscs. These animals are marine and live; near the shore, where they burrow into mud or rocks. The bivalve shell is thin,-and, in roost species, soon ceases to grow; there is, however, an accessory shell secreted by the outer surface of the siphons; this forms a tube open at both ends. A familiar instance of this group- is Aspergillum (q.v.).