Using the materials of Tuyazaki region reported in the first part of the present study, the fruiting period and the conditions of the basal portion of individuals in each species were examined into details with special reference to the formation of floating seaweeds. (1) The fertile individuals of major species of floating seaweeds occur abundantly in the following months (Fig. 1) : 【図】Sargassum fulvellum : March
S. horneri : March ? April
S. tortile : March ? May
Cystophyllum sisymbrioides : March ? May
Sargassum piluliferum : July
S. patens : July ? August
S. serratifolium : July ? August
S. ringgoldianum : Septembe r ? October (2) In the species of summer fruiting period such as S . patens, S. piluliferum, S. serratifolium, etc., the rise in relative abundance of a certain species occurring as floating seaweeds is nearly coincident with the increase in proportion of mature individuals in the same species. Of the species which mature in spring such as S. fulvellum, S. tortile, etc., on the other hand, the period of maturity shows some delay from the rise in quantities of the same species (Fig. 1). (3) Annual Sargassums have a tendency to detach at their basal ho l dfast from the substrata. While in the perennial forms the investigation into the proportion of the individuals with their basal part shows the decreasing order as follows : S. serratifolium → S. patens→C. sisymbrioides. This difference seems to be related to the shape of their basal parts (Figs. 2, 3). (4) It is considered that the formation of floating fucaceous algae occurs mainly at the time of the maximum growth of each species, and that the difference between the rise in relative abundance of a species in winter and its spring fruiting period may partly be attributed to the weather conditions in these months.