Gastrochæna

Gastrochæna, a genus of boring bivalves, not far removed from Teredo and Pholas, but type of a distinct family, Gastrochænidae, which also includes the remarkable Aspergillum (q.v.) and Clavagella (q.v.). The original shell has the two valves typical of Lamellibranchs; but these are delicate, and become surrounded by a secondary tubular shell lining the cavity which the mollusc bores in limestone, coral, other shells, &c. G. modiolina, a rare British mollusc, common in the Mediterranean, makes holes about two inches deep and half an inch in diameter. It sometimes bores right through an oyster into the ground below, and makes for itself, plus little stones and particles of debris, a flask-shaped case, with its neck fixed in the oyster-shell. The tubes of some of the tropical species—e.g. G. elava, from the Indian Ocean, which live in sand are very curious.