38 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



duct opens into the vagina on its dorsal side. It is a long, narrow 

 duct, and expands into a wide sac, the receptaculum seminis, which 

 distally terminates as a long, blind tube (Fig. II, r.cl. and r.s.). The 

 free oviduct is folded upon itself ; distally it opens into the oviducal 

 portion of the common duct, and proximally into the distal end of the 

 vagina. The common duct is richly saculated and almost straight. 



The opening on the left side of the vestibule leads into the penis, 

 a large, oval-shaped, thick-walled sac. The internal structure of this 

 organ is interesting. The walls are thrown into a series of ill-defined 

 plications, and along these, arranged at varying distances, are a series 

 of minute spines, with their sharp-pointed, free ends directed towards 

 the opening at the proximal end. They attain their greatest dimensions 

 at about the middle of the sac, becoming almost invisible to the naked 

 eye at the extreme proximal and distal portions (Fig. III). Examined 

 under a low power of the microscope, each spine is seen to consist of 

 a sharp chitinous body imbedded at one end in a muscular cushion 

 (Fig. IV). At the di.-tal end of this sac is a small penis papilla and 

 the opening of the vas-deferens. 



The penis has a small flagellum at its distal end (Fig. II, fl.). 

 The retractor muscle is inserted in the wall of the ventral side. 

 That portion of the vas-deferens immediately following the penis is 

 a fairly wide tube, and is folded upon itself in the form of a figure 8 

 (Fig. II) ; it soon, however, becomes smaller, lies close to the dorsal 

 wall of the penis and vagina, and, passing beneath the receptacular 

 duct and above the free oviduct, enters the prostatic portion of the 

 common duct. 



