In the present paper the germination of carpospores and tetraspores in Rhodoglossum pulchrum SETCH. et GARDN. (Iridaea pulchrum KÜTZ.) and Iridophycus cornucopiae SETCH. et GARDN. (Iridaea laminarioides BORY) is dealt with. The carpospores and tetraspores present the same size and form within each species, but the size of the spores of these two species is different, the diameter of the former being 35μ and the latter 23μ. The manner of development of the spores was found to be the same in the two species. The spore-cell, without change in size, is first divided into two by forming a perpendicular wall, and further by forming rather irregularly orientated walls it develops to a certain number of cells. After this stage the germling forms usually a deeply red hemispherical disc with a fairly regular outline, then increases iii vertical radius by the marginal growth and subsequently becomes a more flat and expanded disc. Thus in these species the germ discs arise always by direct segmentations of their spore-cells. In germlings of about 20 days old, the first upright shoot develops from the meristem of the upper part of body and many long hyaline hairs spring from the surface of the body, Generally speaking, the germination of the spores in the present two species always takes place in the manner known as the disc-type (“Haftscheibentypus” KYLIN 1917) which is commonly found in Gigartinales, and the smaller spores in I. coruncopiae develops earlier than the larger ones in R. pulchrum and also the hyaline hairs appear on the surface of the germling of the former in a more early stage than the latter. When several sporelings develops close together on a slide in cultivation, they often fuse together into a large disc-body without any distinct limit between them. In I. cornucopiae it was frequently found that parenchymathous filaments resembling in appearance to the germ-tubes protrude from the tetraspore-cell, while in R. pulchrum this is rather rarely met with. It will be interesting to note that the formation of such filaments in these species seems to be related with the germ-tube formation known in some genera of Cryptonemiales, that is, Gratcloupia, Halymenia, Cryploncmia etc.