594 



MEGUMI VERI AND TOKIO KABURAKI : 



across the median line. Behind the pharyngeal folds, the uteri gradual- 

 ly narrow as they proceed backward ; slightly behind the penis, they 

 unite in the median line to form a short unpaired uterine duct before 

 joining the thick-walled median vaginal passage on the ventral side. 



Fig. 3. 



ti vp g pg 



av vb p ed sv vd 



Fig. 3. Genital end-organs of N. fulvoptmctatus in sagittal 



section, diagrammatically shown. 



av accessory vesicle of vagina, ed ejaculatory duct, g 

 gut, p penis, pg prostatic gland, sv seminal vesicle, 

 11 unpaired uterine duct, vb vagina bulbosa, vd vas 

 deferens, vp vaginal passage. 



The vaginal passage is lined with a ciliated columnar epithelium, 

 outside which is a thick muscular coating composed of an internal 

 longitudinal and an external circular layer of fibres. A large number 

 of ductules from unicellular glands, which produce a secretion similar 

 in nature to that of the prostatic gland, open into the vaginal passage 

 through the wall. Posteriorly the passage is continued for a short 

 distance as the wide duct of the large and sac-like accessory vesicle. 

 This vesicle has a wall consisting of a thick glandular epithelium and 

 a fine muscular coating ; in the cavity are contained spermatozoa 

 together with a coagulum of the secretion. In the anterior parts the 

 vaginal passage makes an abrupt downward bend and passes over 

 into a space with a thick and somewhat plicated wall. This space 



