376 MOLLUSC A. 



In the Helicidae there is a hermaphrodite gonad which lies together 

 with the liver in one of the first whorls of the shell (fig. 371, ). A coiled 

 genital duct follows which widens to a thick-walled 'uterus' (u) along 



FIG. 370. Anatomy of Cyprcea tigrfs. (After Quoy et Gaimard.) br, ctenidium; c, 

 heart; d/, vas deferens; /t, liver ; m, stomach ; N, cerebral ganglion ; oc, eye ; pe> 

 penis ; ph, pharynx, the radula drawn out; r, rectum ; re, nephridium; , testes. 



which a second seminal canal appears to lie. Actually in the interior 

 there is but a single lumen, the different appearances being due to glands 

 in the walls. A separation into vas deferens and vagina occurs at the 

 end of the uterus. The vas deferens (vd) proceeds as a small coiled 

 canal to the genital pore. Here it enlarges to a protrusible penis (p) 

 with which is connected a retractor muscle and an appendage, the flagel- 

 lum (fl). The vagina is broader and goes straight to the genital pore, 

 where it meets the penis. Connected with the female genitalia are the 

 large albumen gland (ei) at the beginning of the uterus and a receptac- 

 ulum seminis (r) ; a round vesicle connects with the vagina by a long 

 duct, and (not always present) two ' finger-form glands.' Lastly, the dart 

 sac (ps) of the vaginal wall, which secretes a calcareous stylet, the * love 

 dart,' which in copulation acts as a stimulus to the male genitalia. In 

 spite of hermaphroditism a copulation lasting for days may occur, con- 

 nected with which is the fact that in many species the male cells are first 

 matured, then the female (proterogyny) ; or the reverse may occur 

 (proterandry). 



The sexual opening is almost always on the right side, beside 

 the anus or in front of it on the head. Its position may be rec- 

 ognized in hermaphroditic species and in dioecious males by the 



