The author studied of the detailed structure of the female genital organs in 18 specieses (Table, P. 1924) out of mammalian-, avian-, amphibian- and fish-trematoes and came to the following conclusions: 1) In all specieses the author examied, the terminal end of the ciliated epithelium of the oviduct is limited constantly and sharply at the point slightly peripheral to the point of junction of the oviduct and the common vitelline duct. It seems highly probable that this fact is common for all digenetic trematodes. 2) In Loxogenes liberum, Stellantchasmus falcatus, Echinochasmus perfoliatus, E. japonicus, E. elongatus and Echinostoma gotoi, the “Befruchtungsraum (Looss)” [“Verschluckapparat (Kobayashi)”] developes prominently, while in the other 12 specieses rudimentary. 3) In Stamnosoma armatum, Pygidiopsis summus, Exorchis oviformis and a new species of Exorchis (Exorchis major Hasegawa) the direction of the ciliary movement of the cilia of the Laurer's canal is constantly centripetal (towards the oviduct), while in the other 14 specieses on the contrary constantly centrifugal (towards the dorsal opening of the Laurer's canal.) 4) In all specimens examined, the Laurer's canal opens on the dorsal surface of the body and it seems to eliminate the contents of the seminal receptacle and the oviduct. 5) In Loxogenes liberum and Genarchopsis goppo, a group of especially long cilia is recognizable in the orifice of the seminal receptacle, by its ciliary movement the contents of the latter are constantly stired. 6) In Stamnosoma armatum, the contents of the seminal receptacle are arranged like a whirl. 7) About the relation of the Laurer's canal with the seminal receptacle recognized the author following four types: a) The seminal receptacle itself does not open separatly in the oviduct but is merely a dilated part of the Laurer's canal near its junction with the oviduct. (for example: A new species of Podocotyle and Genarchopsis goppo). b) The seminal receptacle is connected to the Laurer's canal near its junction with the oviduct by a short duct. (for example: Clonorchis sinensis). c) The seminal receptacle and Laurer's canal open together into the oviduct by one orifice. (for example; Stamnosoma armatum and Loxogenes liberum). d) The seminal receptacle and Laurer's canal open separately but very closely into the oviduct. (for example: Metorchis orientalis). 8) In Stellantchasmus falcatus Echinochasmus perfoliatus, E. japonicus, E. elongatus and Echinostoma gotoi, there is no true seminal receptacle.