The microsculpture of Rectartemon depressus (Heynemann, 1868) shell is described on scanning electron microscope. The generics characteristics are proposed: shell's dorsal sculture formed for ribs striae radial; nuclear whorls smooth; ventral surface of the shell smooth or slightly striate; and as specifics characteristics: the number of ribs striae radial on the last world. The R. (R.) depressus presented seven or eight ribs striae radial for millimeter.

This paper registers 16 species of aquatic molluscs, especially the limnic and estuarine species Heleobia davisi Silva & Thomé, 1985, Heleobia australis australis (Orbigny, 1835) and Erodona mactroides Bosc, 1802, from D'Una river and Mirim, Imaruí and Santo Antônio lagoons and Laguna Beach (Santa Catarina, Brazil). This parameter was very important for the paleoecological analysis conduced for that area, where oscillation of the sea level occurred during the Holocen Period. Heleobia davisi is registered for the first time to the Santa Catarina.