Van Geel et al. 1981: Bag-shaped microfossil type. 90-150 μm in length; wall ca. 0.5 μm thick, smooth. HdV 353A - D have in common that they have a large opening at one side originally covered by a valve (= HdV 353C). Characteristic of HdV 353A is the apical appendage.
van Geel B, Bohncke SJP, Dee H (1981) A palaecological study of an upper Late Glacial and Holocene sequence from 'De Borchert', The Netherlands. Rev. Palaeobot. Palynol. 31:367-448.