- Rotational symmetry of cell face outline is 360 degrees; one end is a reflection of the other
In this section
Valves mirror images of each other, each possessing a raphe (genus is biraphid). Distinctively curved and slightly indented on the short edge in some species. Raphe lies beneath fibulae on one edge of the valve (in curved species, this is the short side). Raphes are on the same side on each valve (unlike Nitzschia, in which they are on opposite sides; however, this may be difficult to discern).