Didymosphenia M. Schmidt
Frustules biraphid, large and robust, asymmetrical to transapical axis, symmetrical to apical axis (although some populations are asymmetrical to the apical axis), capitate at both apices, wedge-shaped in girdle view. Marginal ridge of silica on both sides of valves, terminating near the headpole as spines. Septa and pseudosepta lacking. Two-several stigmata occur on one side of the central area. Apical pore field not bisected by the raphe.
Light Microscope Image(s)
Each image is accompanied by the genus and species, California Academy of Sciences slide number (ie. CAS 612010), location of the specimen on the slide, and dimension in microns.