Please note: the images below are not all to the same scale.
Shell shaped like a cap or shield without any sign of helical coiling.
Shell with very a low spire and the mouth aperture is half-moon shaped.
Shell taller than wide. Coiling may be either left-handed (sinistral) or right-handed (dextral). An operculum may or may not be present. (See glossary for details of terms).
Shell coiled more or less in one plane, making it wider than it is tall. An operculum may or may not be present.