The life histories of the red algae Rhodochorton purpureum and R. tenue were studied in unialgal culture. Telrasporophytes produced sporangia in short day regimes (8-12 hr) with 50-200 ft-c cool white light at 10 or 15 C. Mature gametophytes were not observed in the Washington and Alaska clones of R. purpureum. Tetraspores from R. tenue and the California clones of R. purpureum give rise to unisexual gametophytes that are reproductive when smaller than the tetrasporophytes. The tetrasporophytes develop directly from the gonimoblast cells. Because of similarities in morphology and life histories, it is proposed that R. tenue be placed in synonomy with R. purpureum.