The valve margins of Plagiotropis are lanceolate with narrow poles. The valve face is folded, with folds appearing as lines on either side of the raphe. The raphe itself is raised above the valve face and positioned within a keel. The axial area is narrow and the central area is variable in shape. Striae are parallel and composed of loculate areolae. In girdle view, cells appear constricted in the center.
Plagiotropis is an epipelic genus of brackish waters.