Shell rissoiform, with a sinuous labial margin, and often a marked axial sculpture. Operculum horny, with an apophysis on its inner side.
 

« This subgenus is very distinct from Rissoa by its semi-lunar, narrow, sinuous mouth, provided, towards its middle, with edges projected forward and marked, internally and posteriorly, with a depression which represents the beginning of a canal. The operculum is quite remarkable in this section: it is horny, thick, subspiral, semi-lunar, having a smooth whorl above; below, it is marked with a longitudinal depression near the edge of the increasing part; above the depression is a callosity which continues towards the summit, where it forms an elongated projection quite similar to that which one notices in the Nerites. » A. D. d’Orbigny: Voyage dans l’Amérique méridionale… vol.V, part.3 “Mollusques”, Paris 1841, p.395.