A number of samples from salt-pans collected by J. Rooth in Bonaire and by Miss T. M. Emeis in Curasao were handed over to the author for identification. Frémy (1941) has published a list of Cyanophyceae collected by Wagenaar Hummelinck in Bonaire, Klein Bonaire and Curaçao in 1930 and 1932. Among the last mentioned collection there were samples from the same salt-pans in Bonaire, where also J. Rooth did his collecting. It is interesting to compare both results. Dr Fr. Drouet had the kindness to procure some identifications for this part as well as for part II.