Page:Natural History, Mollusca.djvu/308
hinge furnished at one period of life with cardinal teeth. The ligament is external and projecting. The animal is oblong, with the mantle closed, except in front, where exit is afforded for a minute finger-like foot, furnished with a byssal groove. The siphons are united, and their orifices, which are large, are margined with a fringe of simple filaments.