Introduction The development of the fetal membranes and the definitive structure of the placenta have been studied in one or a few representatives of the following families of Chiroptera: Pteropidae (Gohre, 1892a, b; Selenka, 1892; Kohlbrugge, 1913; Keibel, 1922; van der Sprenkel, 1932; Moghe, 1951, 1956; Wimsatt, 1958; Karim, 1971, 1972a), Rhinopomatidae (Srivastava, 1952; Gopalakrishna, 1958), Emballonuridae (Gopalakrishna, 1958; Wimsatt & Gopalakrishna, 1958), Noctilionidae (Anderson & Wimsatt, 1953, 1963), Megadermatidae (Gopalakrishna, 1950b, 1958; Gopalakrishna & Khaparde, 1978a, b), Rhinolophidae (Hamlett, 1934; Gopalakrishna & Bhiwgade, 1974; Bhiwgade, 1976, 1977), Hipposideridae (Gopalakrishna, 1958; Gopalakrishna & Moghe, 1960; Jeevaji, 1973), Phyllostomatidae (Hamlett, 1935; Wislocki & Fawcett, 1941; Fleming, 1971; Rasweiler, 1972, 1974; Bodley, 1974; Bleier, 1975), Desmodontidae (Wimsatt, 1954; Bjorkman & Wimsatt, 1968; Quintero & Rasweiler, 1974), Vespertilionidae (several early authors and, more recently, Wimsatt, 1944, 1945, 1958; Gopalakrishna, 1949, 1950a, 1958; Enders & Wimsatt, 1968; Potts & Racey, 1971; Phansalkar, 1972; Sapkal, 1973) and Molossidae (Hamlett, 1934; Mossman, 1937; Stephens, 1962, 1969; Stephens & Easterbrook, 1968, 1969, 1971; Stephens & Cabral, 1971). These studies have revealed that there are considerable differences among the members of the different families, and sometimes among members of the same family, in the details of the development of the fetal membranes and the final structure of the placenta.