Meloseira nummuloides Ag.
Heiberg and O'Meara assign this species to Lysigonium moniliforme (Muell.) Link, which is not keeled. While Dillwyn's and Lyngbye's figures do not show the keel, it is probable from their descriptions that the angular outline produced by the keel was noticed.
Marine or brackish. Coast of New Jersey; Hudson River (Bail.).
Pl. [1], Figs. 13 and 14.
Gaillonella moniliformis of Bailey is this form, as he describes it as having "two minute projections of the delicate transverse ridges seen near the ends of the two globules belonging to a joint." (Amer. Jour. Science, 1842, p. 89, Pl. 2, Fig. 3.)
Lysigonium Link (1820)
(luo, to loose, and gonu, a joint)
Frustules globose, concatenate; valve simply punctate.
LYSIGONIUM MONILIFORME (MUELL.) LINK
Frustules usually in twos, not keeled; valve with puncta in longitudinal lines, the puncta of the enveloping zone larger and in transverse rows. L. 25-40 µ (De Toni).