Plants of G. furcata were divided into four variant populations. The habit characteristics, external and internal morphology were analysed quantitatively in order to clarify their morphological variation. Among four variant populations, type I(typical G. furcata type) and type II(G. furcata f. intricata type) may be influenced by the time when the develop from the crustose basal discs and the tidal level. Type III is the immature plants, and type IV (G. furcata f. coliformis type) is a G. furcata population in late spring after the luxuriant season. For the reason, the formas of G. furcata f. intricata and f. coliformis are no more valid in Gloiopeltis furcata.