Key to European species:
1. Shell without umbilicus; columella not grooved; periostracum thick; last whorl occupies less than 80% of shell height; yellowish Lacuna crassior
Shell with umbilicus; columella grooved 2
2. Spire high, 5-7 whorls; last whorl occupies less than 90% of shell
height; umbilical groove smooth 3
Spire low, 3-4 whorls; last whorl occupies more than 90% of shell
height; umbilical groove ridged 4
3. Shell turreted; periostracum thick and transversely ridged; without
brown spiral bands on last whorl Lacuna crassior
Shell not turreted; periostracum thin, smooth; usually 4 brown spiral
bands on last whorl Lacuna vincta
4. Spire extremely low; umbilical groove very broad; greenish,
unbanded Lacuna pallidula
Spire low; umbilical groove moderately broad; usually 3 brown spiral
bands on last whorl Lacuna parva