Cystiscidae
Cystiscidae is a taxonomic family of minute sea snails, marine gastropod mollusks or micromollusks. Description. The shell is minute to large, either white, uniformly colored, or patterned; the surface is smooth, sculptured, or axially costate; the spire is flat to immersed, or low to tall; the protoconch is paucispiral; the lip is thickened, smooth or denticulate; an external varix is present or absent; a siphonal notch is present or absent; a posterior notch is present or absent; the columella is multiplicate, internal whorls cystiscid or modified cystiscid type. Mantle cavity with monopectinate ctenidium and bipectinate osphradium. Proboscis pleurembolic; jaws  absent; typical radular sac present. Taxonomy. The family was erected by William Stimpson for a single included species based on unusual features of the head and radula. Subsequent authors included this group in the family Marginellidae. Coan (1965) recognized this group as a subfamily, but he did not include such genera as "Gibberula", "Persicula", and "Canalispira". Rule of priority of the ICZN require that the name Cystiscidae must be used, but this is unfortunate because the type specimen of the type species is lost, and that species is poorly known. 2005 taxonomy. The family Cystiscidae consists of subfamilies (according to  the Working Classification of the Gastropoda by Bouchet et al., 2005): Reference for inclusion of Granulinae in Cystiscidae: Bouchet, P.; Rocroi, J.-P.; Fryda, J.; Hausdorf, B.; Ponder, W.; Valdes, A.; Waren, A. 2005. Classification and Nomenclator of Gastropod Families. Malacologia: International Journal of Malacology. Hackenheim, Germany: ConchBooks. Genera. Genera within the family Cystiscidae include: Canalispirinae Cystiscinae Plesiocystiscinae Abbreviations: Comparisons of shells of the genera: