GEXERATIVE ORGANS OF DIOECIOUS AlOLLUSCA 



135 



ova and the spermatozoa. These glands are generally known 

 as the ovary in the female, the sperm-gland or testis in the male. 



(6) The channels which provide for the passage of the sem- 

 inal products ; namely, the oviduct in the female, the vas deferens 

 or sperm-dnct in the male. 



((?) The external generative organs. 



Dioecious Mollusca. — The common Littorina ohtusata will 

 serve as a typical instance of a dioecious prosobranchiate, exhib- 

 iting the simplest form of organs. In the female the ovary^ a 

 lobe-shaped body, is embedded in the liver. An oviduct with 



:t-Pe 



Fig. 49. — Generative and other 

 organs of Littorina ohtusata L., 

 female. 



M, muscle of at- 

 tachment. 

 0', female orifice. 

 Od, oviduct. 

 Oes, oesophagus. 



Fig. 50. — Generative and other 

 organs of Littorina ohtusata L., 

 male. 

 A, anus. M, muscle of attach- 



Br, hranchia. ment. 



H, heart. Pe, penis. 



I, intestine. Te, testis. 



Li, liver. VD, vas deferens. 



(After Souleyet.) 



A, anus. 

 Br, l)ranchia. 

 Buc, buccal mass. 

 H, heart. 

 Hep, hepatic duct 

 I, continuation of Ov, ovary, 

 oesophagus. Ra, radula. 



Ki, kidney. St, stomach. 



Li, liver. U, uterus. 



(After Souleyet.) 



many convolutions conveys the ova into the uterus, an oblong 

 chamber which consists simply of a dilatation of the oviduct. 

 The ova descend into the uterus, which is sometimes furnished 

 with a seminal pouch. In this seminal pouch, or above it, in 

 the oviduct, the ova come into contact with the spermatozoa. 

 The lower part of the uterus secretes a gelatinous medium (or 



