Nucula (nu kula)

little nut, dim. of пих ( пис- ), a nut.] A genus of acephalous or conchiferous mol lusks, formerly referred to the Arcidæ or ark-shells, now made type of the family Nu culida. The size is small, and the shape resembles that of a beechnut, whence the name. There are about 70 living species, of which Nucula cobboldia. N. nucleus is typical, and numerous extinct ones, among which is N. cobboldiæ of the Eng lish crag. Nuculacea (nū-kū-lā'sē-a), n. pl. [NL., nuculanium (nu-kū-lā'ni-um), n.; pl. nuculania (-a). [NL.,