Valves rhombic-lanceolate, with subacute ends. Striæ, 25 in 10 µ, radiate. Lower valve with stauros widened toward the margin, and cleft into three divisions.
Pavonia, N. J. (artesian well).
Pl. [16], Fig. 13.
I have seen the lower valve only. Cleve states that the upper valve is costate with "alternating fine lineolæ twice as close as the costæ."
Cymbella AG. (1830)
(cymbe, a boat)
Frustules free, stipitate or enclosed in tubes. Valve boat-shaped; median line asymmetrical, straight or curved.
Chromatophore single, covering the entire interior of the frustule, except the ventral part of the zone and the median lines. Its longitudinal axis is on the dorsal part of the zone. A pyrenoid lies in a fold of the chromatophore on the dorsal part.
The genus includes the former genera of Cocconema, characterized by stipitate forms, and Encyonema in which the frustules are frequently enclosed in gelatinous tubes.
Section 1.—Cymbella Proper. Frustules free or sometimes stipitate