236 



COMPARATIVE ANATOMY 



The oviduct which separates from tlie vas deferens at the end of the uterus is also 

 a vagina. It is a simple tube which opens outward to the riglit near the anus 

 through the genital aperture. Near the middle of its course it is joined by the 

 stalk-like duct of a globular vesicle, the receptaculum seminis (bursa copulatrix), and 

 by a long glandular csecal appendage. 



3rd Type. — We find this in tlie Stylo »wud02)hora among the Pulmonata, and also 



r-^' 



Fio. 193.— Anatomy of Helix pomatia (after Leuckart, Wandtafeln). T)ie shell i.s nMiioved 

 and t}ie mantle laid back to the left, the organs of the visceral dome and head are isolated and 

 separated. To the left (in the ligure) are the genital organs. L, Digestive gland (liver) ; Z*?, her- 

 maphrodite gland; ./, intestine; N, kidney; V, ventricle; M, fore-stomach; F, foot; A, anus; 

 Al, edge of the mantle near the respiratory aperture ; Mr, retractor muscle ; G, cerebral ganglion ; 

 Fl, flagellum ; .St, oesophageal bulb (pharynx) ; P, penis ; E, retractor of the tentacle ; I's, dart sac ; 

 AD, digitate glands ; Vd, vas deferens ; A"", lateral bulging of the stalk of the receptaculum seminis 

 (Rs); Oct, portion of the uterus belonging to the oviduct ; /?(?, albuminous gland ; Z<7, hermaphrodite 

 duct. 



in all Niidibranchia and a few Trdihranchia [e.g. Plcurohranrhcea). The herma- 

 phrodite gland gives rise to a hermaphrodite duct, which, as in the second type, 

 sooner or later divides into a male and a female duct. These, however, do not ojien 

 out through distinct apertures, but again unite to form a common atrium genitalc or 

 a genital cloaca. This third type nuiy be deduced from the second by suppos- 

 ing that the male and female apertures became apjiroximated, and finally opened 

 together. 



