Arcuate [adjective]

The frustules are curved or arcuate (arcus, a bow) in the side view, oblong and narrowed at the ends in the front view.

Valve narrow, with arcuate dorsal and straight ventral margin, acute at the ends.

Valve linear, with dorsal margin arcuate and the ventral margin straight.

Valve arcuate, without cost, transversely striated; pseudoraphe absent; pseudo-nodules at each end.

The valves of the auxospore are usually more or less arcuate, as in Cymbella, to which the genus is closely allied.

Valve arcuate on the dorsal and nearly straight on the ventral side; ends protracted or slightly capitate.

Valve arcuate, with several or numerous dorsal ridges or cren which decrease in relative size in proportion to their number.

Rhoiconeis is achnanthiform, with frustules arcuate, and the species is named by Cleve Achnanthes trinodis (Arnott).

Valve linear, arcuate on the dorsal, straight on the ventral side, reflexed at the extremities.

During all these changes, while the zygospore enlarges, the wall of the arcuate cells becomes coloured brown.