128 



THE GASTROPODA 



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Nudibranchs, the stylet being contained in a special pouch in 



certain species of Doris, in some other Nudibranchs there are 



multiple stylets. 



In addition to the bursa copulatrix, there are numerous and 



various accessory genital organs in the hermaphrodite Gastropoda. 



An albuminiparous and a mucous gland are found on monaulic ducts, 



generally near their distal end (Fig. 171, 

 mm). In the diaulic Pulmonata there 

 is a large albuminiparous gland on the 

 hermaphrodite section of the duct (Fig. 

 104, E.d), and on the female part of the 

 duct of Basommatophora there is an 

 albumen gland corresponding to the 

 uterine glands of Stylommatophora (Fig. 

 104, u). The diaulic and triaulic Opis- 

 thobranchs have also contiguous albumen 

 and mucous glands on the oviducal part 

 of the genital duct. The terminal portion 

 of the oviduct of Stylommatophora is 

 further provided with a glandular zone 

 (Zonites), or with two multifid vesicles 

 with a variable number of ramifications 

 (Fig, 104, d). Opening between the 



\ O * / i O 



tus, dorsal aspect, n.d, aibumini- two is a special pouch seemingly a 



parous duct; a.g, albuminiparous ... -, ,. . , . , , . . 



Kland; h.rf, hermaphroditic duct ; Specialised multifid VCSlcle, which Secretes 



dua? v ian?rio,^^ a snar P calcareous dart (Fig. 104, p.s). 



no, oviduct;' ji, ' penis ; pr, pros- Before copulation the dart-sac is evagin- 



tate ; r.., recepteculuni somims ; xp, . " 



spermidiu-.t ; vo, vulva. ated together with all the terminal 



part (vestibule) common to the repro- 

 ductive organs, and the dart, which is caducous, pierces the 

 skin of the conjugate. The spermiduct is sometimes furnished 

 with a more or less elongate " prostate " gland, as in Falvata, 

 Onddiopsis (Fig. 103, pr\ various Bullomorpha and Elysiomorpha 

 (Fig. 105, pr). The penis of certain Stylommatophora is provided 

 with a long hollow caecum, the "flagellum" (Fig. 104,/), in the 

 interior of which is secreted the spermatophore or capreolus. 

 This is a thin-walled chitinous tube closed at one end and cleft 

 at the other and filled with a quantity of sperm. When there is 

 no flagellum the spermatophore is formed by the deeper portion 

 of the penis. Sometimes the spermatophores are furnished with 

 denticulations and even with arborisations (Fig. 106). 



The hermaphrodite gland (gonad) does not liberate ova and 

 spermatozoa simultaneously, the discharge of the former occupying a 

 very short time after copulation. Generally speaking, the herm.iph- 

 roditism is protandric, the spermatozoa being the first of the 

 genital products to come to maturity. This hermaphroditism is 



Fia. 105. 



i, reproductive appara- 



