Fallacia spp.is widely distributed in intertidal sediments as an important component of benthic diatom flora.Cells of Fallacia are usually around 10μm.Fine detailed structures of those species could not be well resolved by light microscopy (LM).Thus it is difficult and often inaccurate to identify the small-celled Fallacia taxa only based on morphological feature with LM.It is necessary to investigate those taxa by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).