=Hermaphrodite Mollusca.=--(_a_) _Monogonopora._--The reproductive system in the hermaphrodite Mollusca is far more complicated than in the dioecious, from the union of the male and female organs in the same individual. As a type of the Monogonopora, in which a single orifice serves for both male and female organs, may be taken the common garden snail (_Helix aspersa_), the accompanying figure of which is drawn from two specimens found in the act of union (Fig. 53). [Illustration: FIG. 53.--Genitalia of _Helix aspersa_ Müller, drawn from two individuals in the act of union, from a dissection by F. B. Stead. =A.G=, albumen gland. =C=, coecum. =Cr=, crop. =D.S=, dart sac. =E=, eye (retracted). =Fl=, flagellum. =H.D=, hermaphrodite duct. =H.DF=, ditto, female portion. =H.DM=, ditto, male portion. =H.G=, hermaphrodite gland. =L=, liver. =M.G=, =M.G=, mucous glands. =Ov=, oviduct. =P.S=, penis sac. =R.M=, retractor muscle of penis. =Sp=, spermatheca. =V=, vagina. =V.D=, vas deferens.] Beginning from the inside and proceeding outwards we have firstly the _hermaphrodite gland_ or _ovo-testis_ (H.G.), a yellowish white mass of irregular shape, embedded in the _liver_ (L.) and forming part of its spiral but not reaching quite to the apex. Within this gland are developed the ova and spermatozoa. The former are rather large round cells, produced within the outer wall of the gland, while the spermatozoa, which are produced in the more central part, are thread-like bodies, generally aggregated in small bundles. From the hermaphrodite gland the ova and spermatozoa pass through the upper part of the _hermaphrodite duct_ (H.D.), which is always more or less convoluted. Below the convoluted portion, the duct opens into the _albumen gland_ (A.G.), a large linguiform mass of tissue which becomes dilated at the time of pairing, and secretes a thick viscid fluid which probably serves to envelop the ova. Up to this point both the male and female elements follow the same course, but on their exit from the albumen gland they diverge. The hermaphrodite duct becomes greatly enlarged, and is partially divided by a kind of septum into a male and female portion. These run parallel to one another, the larger or female portion (H.DF.), through which the ova pass (and which is sometimes termed the _uterus_) being dilated into a number of puckered folds, while the smaller or male portion (H.DM.) is comparatively narrow, and not dilated. At their anterior end, the two portions of the duct separate completely from one another, the female portion being then termed the _oviduct_ (OV.) and the male portion the _vas deferens_ (V.D.).