The life history of the polyclinid ascidian, Parascidia flemingii was studied in the laboratory from its larval stage to the blastozooid stage. This species is like Circinalium concrescens (Sidnyum turbinatum?) in its external appearance. The present study showed, however, that they were different from each other in 1) larval size, 2) larval activity, 3) spot formation in the adult, and 4) mode of budding. Budding of oozooids occurred 19–32 days after metamorphosis, and 2–8 strobilae were formed in the abdomen and postabdomen. Mother zooids have four stigmata1 rows and two atrial languets, blastozooids having 5–8 stigmata1 rows and a simple languet.