Although the Indonesian Archipelago is phycologically rather well-known, information about the freshwater algae in New Guinea is very scanty. There are only a few papers, e.g. by Bernard (1910) and Cholnoky (1963), but these give only a glimpse of the phycocoenoses of the New Guinea lakes, especially those of the high mountains. Many of these lakes have been mentioned in travel books, and some seem to be promising localities for freshwater algae. The biogeographical relations between Malesian and Australian regions have been much discussed. A number of biogeographers have attempted to unravel the complex of transition in this part of the world. Phytogeographers often accept the Torres Strait as a boundary between the Malesian and the Australian floras. This is only true in a general statistical way; the flora of the dry savannahs of the southern lowland shows a great similarity to that of northern Australia, while the high-mountain flora shows distinct affinities with both the northern temperate Asiatic flora and the temperate South Pacific flora. Zoogeographers, however, include New Guinea mostly in the Australian region because of the existence of a land-bridge between Australia and New Guinea during past geological epochs (see fig. 11—5, in Knight, 1965). In this connection the character and relations of the freshwater algal flora of New Guinea is of some interest. It has been shown by Scott & Prescott (1958) that the freshwater algal flora of northern Australia is closely related to that of the Indo-Malayan region.