B, buccal mass; m, retractor muscles of the buccal mass; ov, ovary; od, oviduct; i, coils of intestines; ao, aorta; c', left auricle; c, ventricle.
Germary and ovary paired; oviduct absent; young viviparous.
True viviparity, that is the development of the ova within the oviduct, is very rare, occurring only in one case among the Amphineura and in some aquatic and pulmonate Gastropoda.
The yolk prepared by the latter is conducted by one or more specialized ducts to the oviduct and the point of union is distinguished by the opening of a " shell-gland " which secretes a membrane around the conjoined mass of ovum and yolk.
From this junction there proceeds an oviduct or " uterus " (paired or single) which before opening to the exterior expands to form a muscular protrusible pouch - the bursa copulatrix.
Stevens the socalled oviduct acts only as a "sperm-duct" or receptaculum seminis.
Each oviduct, after a short course, becomes dilated into the uterus.
Genital opening subterminal, behind the last pair of fully developed legs; oviduct without receptacula seminis or receptacula ovorum; the terminal unpaired portion of vas deferens short.
The following species are aberrant in respect of these characters: Peripatus (Opisthopatus) cinctipes, Purcell (Cape Colony and Natal), presents a few Australasian features; there is a small receptaculum seminis on each oviduct, some of the legs are provided with welldeveloped coxal organs, the feet have one anterior, one posterior and one dorsal papilla, and the successive difference in the ages of the embryos in the uterus, though nothing like that found in the neotropical species, is slightly greater than that found in other investigated African species.
There appears to be evidence that some species are occasionally or normally oviparous, and in the supposed oviparous species the oviduct opens at the end of a papilla called from its supposed function an ovipositor, but the oviparity has not yet been certainly proved as a normal occurrence.
Genital opening between the legs of the penultimate pair; oviduct provided with receptacula seminis and ovorum; unpaired part of vas deferens long and complicated; accessory organs of male opening at the sides of the anus.
Genital opening subterminal behind the last pair of legs; oviduct with receptaculum seminis, without receptaculum ovorum; unpaired part of vas deferens very short; accessory glands two, opening medianly and dorsally.
Genital opening between the penultimate legs; oviduct with receptacula seminis and ovorum; unpaired part of vas deferens long; male accessory glands two, opening medianly between the legs of the last pair.
2), says, " Krohn stated that the structures described by my father as ovaries were in reality salivary glands, also that the oviduct runs down to the orifice described in the Monograph of the Cirripedia as the auditory meatus."
In these forms the pregnant female, instead of laying eggs, as Diptera usually do, or even producing a number of minute living larvae, gives birth at one time but to a single larva, which is retained within the oviduct of the mother until adult, and assumes the pupal state immediately on extrusion.
The oviduct of Lumbricus) are parts of the coelomic wall itself, which have grown out to the exterior.
We have here clearly a case of a true coelomoduct performing the function of an oviduct in both leeches and Eudrilidae.
In the former, the duct, leading from the ovarian sac, and swelling along its course into the spherical sac, the "spermatheca," is highly suggestive of the oviduct and receptaculum of the Eudrilidae.
In some forms this receptacle acquires a separate external opening remaining connected with the oviduct internally.
M The "bell" swallows the matured embryos and passes them on into the uterus, and thus out of the body via the oviduct, which opens at one end into the uterus and at the other on to the exterior at the posterior end of o.-- the body.
(The ovary (a) leads into (bb) the oviduct, which is joined at (g) by the duct of the yolk-glands (h, h, Y).
A, a segment of Bothriocephalus latus, showing the generative organs from the ventral surface; ex., excretory vessels; c., cirrus; c.p., cirrus pouch; v.d., vas deferens; v.o., vaginal opening; v., vagina; sh.g., shell-gland; od., oviduct; ov., ovary; y.g., yolk-gland; y.d., its duct; ut., uterus; u.o., uterine opening; the testes are not visible from this side; X 23 (from Sommer and Landois).
In all the species except the African species there is a globular receptaculum seminis opening by two short ducts close together into the oviduct, and in the neotropical species there is in addition a small receptaculum ovorum, with extremely thin walls, opening into the oviduct by a short duct just in front of the receptaculum seminis.
In some families, as many freshwater snakes, the sea snakes, Viperinae and Crotalinae, the eggs are retained in the oviduct until the embryo is fully developed.
B, anterior portion more highly magnified (from Marshall and Hurst, after Sommer); cs, cirrus sac; d, ductus ejaculatorius; f, female aperture; o, ovary; od, oviduct; p, penis; s, shell-gland; t, anterior testis; u, uterus; va, vp, vasa deferentia; us, vesicula seminalis; y, yolk-gland; yd, its duct.
The ovary (a) leads into (bb) the oviduct, which is joined at (g) by the duct of the yolk-glands (h).
From the oviduct a long duct full of yolk passes backwards almost to the hinder end of the body and ends blindly in a globular dilatation just below the skin.
A canal (Laurer's canal) leads from the oviduct or yolk-duct to the dorsal surface.