During the Indian Ocean Expedition of R/V METEOR phytoplankton samples were taken with a multiple closing net (Multinet) at 103 stations. In this material the diatoms were investigated. In all 247 taxa could be identified which belong to 242 species and 5 varieties of formae of 80 genera. Of these 1 variety, 15 pecies, and 3 genera are newly described. New combinations were made for 18 species, and a number of old combinations was reinstated.

Relative abundances are noted for each of the subareas. The abundance is given in letters: D = dominant, practically only one species present (very rarely observed and not used in the list, due to generalization), A = abundant, F = frequent, L = less frequent, R = rare, S = very rare, empty = absent. If a species was found in more than half of the stations of a given subarea, its degree of presence therefore high, the abundance is noted in capital letters (D, A, F, L, R, S). In this case the average abundance in that particulare subarea is noted. If a species occurred in less than half of the stations of a subarea, its occurrence was considered to be "scattered" (low degree of presence) and noted by a lower-case letter (d, a, f, l, r, s). In this latter case the notations were biased toward s higher frequencies, e.g. if a species was observed to be rare in five station, but frequent in two, an f would be given.

Supplement to: Simonsen, R (1974): The Diatom Plankton of the Indian Ocean Expedition of RV "Meteor" 1964 - 1965. Meteor Forschungsergebnisse, Deutsche Forschungsgemeinschaft, Reihe D Biologie, Gebrüder Bornträger, Berlin, Stuttgart, D19, 1-107