24 



Art 2. — T. Kaburaki : 



opening directly leads into the vestibulum which anteriuiiy com- 

 municates v/ith the penis-sheatli. 



The small testes occur in the 

 ventral parts of the body, averaging 

 about 60 in total number. Some- 

 times they begin to exist in front of 

 the ovaries. More usually they are 

 found close behind these and occur 

 backwards on both sides of the an- 

 terior gut trunk, but laterally to the 

 posterior gut trunks, dowai to the 

 level of the genital opening, and 

 behind this point between the gut 



trunks. 



The fine testicular canal arising 



from the testes cannot clearly be 

 made out. The vasa deferentia, 

 swollen at the posterior one-fourth 

 of the pharynx, proceed backw^ards 

 along the inner side of the longi- 

 tudinal nerve cords and unite into 

 a short common duct in the antero- 

 superior part of the penis-bulb be- 

 fore opening into tlie small seminal 

 vesicle. The vas deferens, wdiich is 

 filled with spermatozoa, is lined w^ith 

 a thin epithelium, outside which in 

 the neighbourhood of the penis a 

 layer of muscular fibres occurs tan- 

 gled to a certain extent. 



The penis is composed of the 

 semispherical bulb of muscular 

 nature and the conical and massive 

 intromittent part which is horizontally disposed in the penis- 

 sheath. The seminal vesicle is of small size and soon com- 

 municates through a very short slender duct witli a relatively wide 



Text fig. 8. Diagrammatic repre- 

 sentation of the orgonization of 

 Planaria vivida Ij. et Kab., as seen 

 from the dorsal side. 

 Viï common vas deferens. 



Other letters as in text figs. 2, 5 

 and 6. 



