Neidium hercynicum

Valves are narrowly elliptic, with broadly rounded apicies. The axial area is slightly diagonal and gradually tapers toward the central area and ends. Proximal raphe ends are short, deflected in opposite directions, and thinner than the middle portion of the raphe. Distal raphe ends are also thinner than the main portion of the raphe and they extend over the distal valve margin. The central area has a diagonal to diamond shape. Longitudinal canals are present on either side of the valve, usually marginal, sometimes submarginal, and are either linear or, in some specimens, concave at the apicies. In the center of the valve, the striae are distinctly oblique at an angle of 23° to 28° from the central sternum. At the apices, the striae may nearly parallel. Stria density is high and may be difficult to resolve under LM. In some specimens, Voigt discontinuities are prominent.