PRELIMINARY DESCRIPTIONS OF SOME JAPANESE TRICLADS. 



165 



in total number, situated ventrally in body. Sometimes they begin to 

 exist from before ovaries. More usually they are found from close behind 

 these backwards on both sides of anterior gut trunk but laterally to post- 

 erior gut trunks down to the level of genital pore, and behind this point, 

 between the gut trunks. Vasa deferentia swollen along posterior one- 

 fourth of pharynx, united into a short common duct in the antero-superior 

 part of penis bulb before opening into the small vesicula seminalis. Ductus 

 ejaculatorius wide, slightly narrowed in the middle parts. Intromittent 

 part of penis conical, horizontally lying. Ovaries two, situated ventrally be- 

 tween first and second branches of anterior gut trunk. Oviducts unite into 

 a single duct before opening into genital atrium from above. Receptaculum 

 seminis very large. Vagina unusually wide, gently constricted in the 

 middle of its course. 



In external habitus the species closely resembles PI. alpina Dana. 



Localities : — Cool running waters in following places : 

 Nikko ; Usui mountains ; hilly districts in provinces Rikuchu, 

 Mutsu, Ugo, Iwashiro, &c. The species is the commonest in 

 mountain streams of the parts of Japan indicated above. 



9. Planaria pellucida, n. sp. 



Woodcut 18. 



In shape this species closely resembles the preceding. 

 Frontal margin subtruncate, weakly crenate. Rounded 

 auricular lobes scarcely prolonged into tentacles, anyway 

 shorter than in PI. vivida. 



Large specimens in the creeping state measured 10 mm. 

 long by about 1 \ mm. across in the broadest part. 



Body colorless, translucent, but with digestive tracts 

 showing themselves in a milky white or a somewhat 

 yellowish or a darkish color. 



Eyes two, situated far behind frontal margin ; distance 

 between them shorter than distance of either eye from lateral 



1 



y 



18. Planaria 

 pellucida, n. sp. 

 Outline of body 

 in the creeping 

 state. 



about 7 X. 



