Shell surface variability of hypselostomatid genera A finely dimpled, pasty surface B strong, raised spiral striae occasionally crossed by radial growth lines C very fine, dense spiral striation occasionally crossed by radial growth lines D rough, wrinkled (sandpaper) surface E weak, non-raised spiral striae crossed by radial lines F reticulated, consisting of rib-like radial growth lines which are crossed by equally strong spiral striae.