748 



ZOOLOGY 



SECT. 



herr, 



rec.serii 



In a very limited number of Gastropoda the gonad opens into 

 the nephridium. 



The sexes are separate in nearly all the Streptoneura, united 

 in the Euthyneura. Special gonoducts are present, except in one 

 or two forms in which the nephridia perform that function. In 

 the unisexual forms the reproductive apparatus is of a compara- 

 tively simple character, consisting merely of a racemose repro- 

 ductive organ, ovary 

 or testis as the case 

 may be, situated dor- 

 sally in the visceral 

 spiral, with the gono- 

 duct opening far for- 



7ierrnd^\ / cilhcl wards on the right- 



hand side, and, in the 

 male, a penis, which 

 is grooved longitudin- 

 ally and non-retractile. 

 In the hermaphrodite 

 forms, such as the 

 Pulmonata (Fig. 640), 

 on the other hand, a 

 considerable degree of 

 complexity is observ- 

 able. There is an 

 ovotestis or "herma- 

 phrodite gland" (her in. 

 gl., Fig. 641, A) some 

 of the follicles of which 

 produce ova, while 

 others produce sperms, 

 a convoluted " Iterma- 

 phrodite duct ' (herm. 

 d.), an albumen-gland, 

 in which the albumen 

 of the relatively large 

 eggs is formed, and 

 sometimes a separate 

 oviduct and sperm duct 

 leading to a common 



genital opening; sometimes there is a single duct undivided through- 

 out. A receptaculum seminis (rec.sem.) is connected with the oviduct, 

 and also a number of narrow accessory oviducal glands (muc. gl.} ; 

 frequently a gland termed prostate is connected with the sperm duct, 

 and there is an eversible sac the sac of the dart (d. s.) containing a 

 crystalline stylet, and a penis (pen.), which is perforated by a canal 

 and is capable of being retracted by a special muscle. The duct 



muc.cpl.ap 



FIG. G40. Reproductive organs of Helix, alb.yl. albumen- 

 gland ; d. s. dart-sac ; flay, rlagellum of the penis ; 

 herm. gl. hermaphrodite gland or ovotestis ; herm. d. duct of 

 ovotestis ; muc. gl. mucous gland ; mv.c. //?. op. apertures of 

 mucous glands into vestibule ; odd. oviducal part of the 

 common duct ; odd. ap. aperture of oviduct into vesti- 

 bule ; pen. penis ; rec. sem. receptaculum seminis ; rec. 

 sem. ap. aperture of receptaculum seminis ; xp. d. sperm 

 duct; sp. d'. spermiducal part of common duct. (After 

 Pelseneer.) 



