A collection of samples containing algae from the salines of Bonaire was brought home by Mr P. Wagenaar Hummelinck from his trips to the Netherlands West Indian Islands in 1930 and in 1936—1937. Though these trips were chiefly undertaken in order to gather zoological material (1, 2) 1), the collector paid attention to botanical objects as well, results of which are to be found in eight earlier papers (3—10). Several data concerning Bonaire can be learned from Mr Wagenaar Hummelinck’s publications. The island, having an area of about 265 km2, is chiefly composed of quaternary limestone (coralrocks), which forms a large plateau in the North East and the South. The Northwestern part of the island is much higher and more indented. Klein Bonaire, having an area of only 7 km2 and situated ¾ km West of Bonaire, consists of a low limestone plateau only.