Eunotiinæ.—Valve lunate; a raphe sometimes partially formed with terminal nodules near the edges.
DIATOMINÆ
Diatoma.—Frustules in filaments. Valve linear or elliptical, costate.
Plagiogramma.—Frustules in fasciæ or free. Valve costate.
Opephora.—Valve costate, with an inner punctate stratum.
Diatoma De Candolle (1805) em. Heib. (1863)
(diatemno, I cut in two)
Frustules oblong or quadrate, adnate in filaments, attached by alternate angles and finally separating. Valve linear or elliptical, with transverse costæ and rows of puncta and a pseudoraphe.
Chromatophores large granules without definite arrangement. (See Pl. [40], Fig. 11.)
DIATOMA VULGARE BORY.