A floristic study on the Japanese soil algae by means of cultures of soil samples has taken. The following results are noteworthy.
1) The following algae are the most abundant species in Japanese soils ; viz. Chlorococcum spp. (including several not identified species), Hormidium flaccidum A. BR., Stichococcus bacillaris NAEG., and Monodus subterraneus PETERSEN.
2) The cultivated soils have the most complicated algal vegetations, and the alpine and forest soils have relatively poor vegetations.
3) Fifty-one kinds of Chlorophycean algae, tweleve Xanthophycean algae, two Euglenophycean algae, fifteen Bacillariophycean algae and twenty-seven Cyanophycean algae are recognized from the Japanese soils.
4) The following algae are new records from Japan, viz. Gongrosira terricola BRISTOL, Chlorococcum echinozygotum STARR, Bracteacoccus irregularis (PETERSEN) STARR, Palmellococcus protothecoides (KUETZ.) CHOD. Monodus subterraneus PETERSEN, Monodus dactylococcoides PASCHER, Monodus acuminata CHODAT, Chlorocloster inaequaris PASCHER, Characiopsis minima PASCHER, Bumilleria exilis KLEBS, Monocilia viridis GERN., Monocilia mainxii (VISCHER), Westiellopsis and prolifica JANET.
5) Rhaphidonema terrestre sp. nov. and Eucapsis terrestris sp. nov. are new to science.