Japanese Freshwater Trie! ads. AQ 



Tlie paired ovary, wliicli is of a >])lierical sliai)e, is placed 

 ventrally between the first and second pairs of tlie gnt branches. 



The vitelhne ghmds, which aie represented l)}^ branching 

 cords of cells arranged in single or double rows, are extensively 

 distributed almost throughout in the interspaces between the gut 

 l>ranches and communicate with the oviducts by means of the 

 short branches of the latter, which are situated at tolerably 

 regular intereals. 



The oviduct starts from the postero-lateral part of the ovary 

 as an ampullaceous passage, which soon narrows and runs back- 

 wards just along the outer side of the nerve cord. At the end it 

 unites with its fellow of the opposite side into a short single duct 

 at a point dorsal to the atrial diaphragm, to oi'ien into the ves- 

 tibulum just behind the latter. 



The seminal receptacle is simply tubular at an eaily stage of 

 development. T^ater, the anterior blind end becomes bent to the 

 right or branches somewhat in the shape of a Y. Its direct wall is 

 an epithelium made up of cyhndrical cells of a glandular nature, 

 which are of a greater height on the ventral than on the dorsal side. 

 The cells appear to have been în high secretory activity, and are 

 observed to be vacuolated. Outwardly there exist two layers of 

 internal circulai' and external longitudinal muscular fibres. 



Posteriorly the receptacle passes over into the vaginal canal 

 which opens dorsally into the vestibulum on the left of the median 

 line. This is constructed in the same manner as the recept;K*le. 



Polycelis ijhuai Kab. 



(P]. T., fig-. 15.— Text fig. 14.) 



Some specimens of this species were captured by the late Pi'o- 

 fessor I.iiMA in the autumn of 191G from Lake Shikotsuko in Hok- 

 kaido. The genital organs were not yet developed in most of them. 



Form and Dniwn.von. — In shape the worm conforms to the 

 outline of the preceding species. The frontal margin is subtruncate 

 and presents in the median part a gentle convexity which laterally 

 passes through a slight concavity into the frontal margin of the 



