PRELIMINARY DESCRIPTIONS OF SOME JAPANESE TRICLADS. 167 



longitudinal zones which converge and meet in front and thus form ^a 

 horseshoe-shaped tract, situated a considerable distance apart from head 

 margin both in front and laterally ; posteriorly the tract extends to about 

 the third pair of gut branches. 



Mouth situated at about between middle and posterior thirds of body. 

 Pharynx inserted at about the middle of body or slightly in front of it. 

 Anterior gut trunk with 8 or 9 pairs of branches ; each posterior gut trunk 

 with 18-20 lateral branches and about as many, but extremely short, 

 innerly directed branches. 



Genital pore situated behind mouth at a distance equal to about one- 

 third that between mouth and posterior body-end. Atrium divided into 

 two cavities. Testes about 18—22 in number on either side, lying ventrally 

 along both sides of anterior gut trunk, extending from ovarian region to 

 the insertion of pharynx. Vasa deferentia opening separately into vesicula 

 seminalis on the sides. Wall of the latter thrown into irregular folds. 

 Ejaculatory duct narrow, opening at tip of penis. Penis bulb spherical ; 

 intromittent part of penis conical, horizontally directed. Ovaries two, 

 placed ventrally between first and second, sometimes between second and 

 third, branches of anterior gut trunk. Oviducts unite into an unpaired 

 common duct on the dorsal side of penis sheath ; the unpaired duct opens 

 into genital vestibulum dorsally and to the left of vagina. Receptaculum 

 seminis dorsally situated, U-shaped and clasping from behind the posterior 

 end of pharyngeal chamber. Vagina runs over penis sheath somewhat to 

 the right of median line, at the end passing into genital vestibulum from 

 above. 



Locality : — Common in the clear brook flowing through the grounds of 

 Sapporo Agricultural College in Hokkaido. Collected by Ijima, Oct. 191 3. 



11. JPoiycclis auriculafa, n. sp. 



Woodcuts 21 and 22. 



Frontal margin subtruncate, with a gentle median convexity. Head 

 end produced laterally into moderately distinct tentacles, rounded at tip 



