Figure 37. Geographic distribution of Didymocyrtis tetrathalamus. 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, Popofsky (1913); B, Original; C, Original; D, Original; E, Original; F, Original.