Figure 53. Geographic distribution of Lithelius nautiloides. N: total number of positive records [total number of samples where the species was presumably sought], for water-column (above 150 m and below 150 m; plankton and sediment trap materials) and surface sediment materials. Sources: A, Boltovskoy (1999); B, Petrushevskaya (1965); C, Boltovskoy (1999); D, Boltovskoy et al. (1983); E, Boltovskoy et al. (1983).