The Ultrastructure in conchospores of Porphyra haitanensis has been observed underelectronic microscope. Each conchospore is bounded by a thin layer of protoplasmic mem-brane. Within the cytoplasm there is a single stellate chloroplast. There are fusions betweenthe chloroplast envelope and plastid stroma. Thylakoids are separated from one anotherby intervening layers of stroma. Granunles of protein-pigment complexes (phycobilisom-es) are orderly arranged on the surface of the thylakoids. Pyrenoid is an electron dense body in the chloroplast stroma, sometimes, but notalways, it is traversed by derivatives of the thylakoid system. Grains of polysaccharide reserved material,--floridean starch, scatter freely in thecytoplasm. Plastoglobuli can only be found in the stroma of plastids. Only a few lipid bodies are present in the cytoplasm. The nucleus is egg-shaped and contains a single spherical nucleolus. There arenuclear pores distributed on the nuclear membrane. Other materials, such as vacuolesribosomes and mitochondria are also observed in the cytoplasm.