Terrestrial Planarians from Japanese Territories. 29' 



The common genital opening leads into the vestibulum which 

 receives the openings of the penis-sheath and the glandular organ. 

 The actual wall of the vestibulum is an epithelium made up of 

 ciliated columnr cells, beneath W'hich are a muscular coating 

 composed of circular and longitudinal fibres. 



Numerous testes, each nearly spherical in shape and made up 

 of sperm-mother-cells and spermatozoa in several stages of develop- 

 ment, are placed colosely together in the ventral portion of the 

 body, arranged in a single row just outside the longitudinal nerve 

 cords, which extend from somewliat behind the ovary to the 

 insertion of the pharjaix. The vasa deferentia, filled up with sper- 

 matozoa, proceed backwards along the outer side of the nerve cords 

 and form a loop at the sides of the penis, to pursue a forward 

 course. After entering the base of the penis, they unite into a 

 single duct which joins the seminal vesicle from the front. 



The penis consists of the semi-spherical bulb of muscular 

 nature and the conical intromittent part which is horizontally'' 

 disposed in the penis-sheath. The bulb contains a relative^ 

 narrow and smooth -walled seminal vesicle, which posteriorly nar- 

 rows gradually into the ejaculatory duct, opening into the penis- 

 sheath at the tip of the penis. The penis-sheath communicate» 

 with the vestibulum through the ciliated tubular passage. 



The ovaries are nearly oval in shape and are present in a pair 

 somewhat behind the brain, one on the lateral side of the nerve 

 cord. From the inner lateral aspect of the ovary starts the oviduct 

 as an ampullaceous passage, which soon assumes the character of a 

 narrow tube, proceeding straight backwards just along the inner side 

 of the vas deferens and receiving the vitelline glands at several 

 points of its course. The vitelline glands are represented by 

 irregularly ramified, cellular cords, extensively distributed in the 

 interstices between the gut branches. The mode of their connexion 

 with the oviduct is effected by means of the short branches of the 

 latter, which are situated at fairly regular intervals. Behind the 

 common genital aperture the oviduct, supplied with numerous 

 unicellular glands, bends inwards, at the same time rising upwards, 

 to fuse with its fellow of the opposite side into a very short 



