Japanese Freshwater Triclads. ^y 



was not clearl}' made out. In the region of tlio penis-sheath the 

 duct l)ends inwards, rising upwards at the same time, and finally 

 unites with its fellow of the opposite side into a single common 

 duct, which opens into the vestibulum from above. 



The seminal receptacle is represented by a slender tubular 

 organ, which extends forward, without forming any widening, up 

 to the dorsal side of the hind end of the pharyngeal chamber. The 

 organ is lined with an epithelium made up of columnar cells of a 

 glandular nature, beneath which comes a thin musclar layer. 

 Posteriorly the receptacle passes into the vaginal canal, which runs 

 dorsal to the penis, finally opening into the vestibulum. 



JPoIycelis karafto Tj. et Kab. 



(PI. I., ficv. 16.) 



This species was procured by the late Professor Ijima in June, 

 19U6, together with PL pellucida, from cool running brooks in the 

 wooded hills to the oast of Tayohara (Vladimirofka), Saghalin. It 

 was also found in a spring near Tretia Padi, north of Korsakoff, in 

 the same island. 



Form and Dimension. — The head is shaped nearly as in both 

 the preceding Folycelis-s])eG\es, but the tentacles are somewhat 

 longer and more pointed at the end. The trunk is slender, almost 

 uniformly broad for the most part and obtusely pointed at the 

 posterior extremity. In the creeping state a large specimen was 

 12 mm. in length and 2 mm. in the broadest part. Commonly 

 the worms are smaller, their breadth equalling about one-fifth or 

 one-sixth the length. 



Colouration. — The colour of the dorsal surface is dark brown 

 with two longitudinal ill-defined darker bands, which run on either 

 side of the median line posteriorly from the neck-like region. The 

 ventral surface is of a lighter colour, showing the course of the 

 longitudinal nerve-cords as two dark lines. 



Fyes. — Numerous small eye-spots are found along and close to 

 the margins of the head, on both sides extending behind to about 

 the second pair uf the gut branches. They are arranged in a single 



