The fine structure of the membrane of cell organelles appearing in the atypical spermatid of Cipangopaludina malleata Reeve has been studied in thin sections by an electron microscope. The porous structure has been revealed in the wall of the flattened sacculus consisting the Golgi complex. The walls are calculated 35 A thick. The mitochondria consist of a small number of tubules and an osmiophili