Japanese Freshwater Triclads. 



25 



and smooth-walled lumen, which posteriorly narrows slightly into 

 the ejaculatory duct. Embedded in the parenchyma around the 

 penis-bulb are the eosinophil penis-glands, which open into the 

 lumen of the penis. 



Text fig. 9. Sagittal section of genital organs of PL ririda, diagrammatically shown. 

 Index letters as in text figs. 2,4,6 and 8. 



As was noted in my previous paper (43), it is an interesting 

 fact that a sperinatophore, apparently completely formed and ready 

 for ejection by the penis, was found lodged in the terminal swell- 

 ing of the common vas deferens or the seminal vesicle, completely 

 filling it up and to a degree distending the same. It is of a nearly 

 pyriform shape, bent at the pointed end and measuring 216/^ by 

 133 f^. The body is so oriented that its pointed end is directed 

 towards, and projects somewhat into, the distal end of the common 

 vas deferens. The capsule is 0-5-3 /^ thick, being thickest towards 

 the pointed end. Its substance is not homogeneous but exhibits 

 a porous structure when seen under the high power. Microchemic- 

 ally It sliows special affinity for eosin, quite agreeing in this 

 respect with the secretion of the penis-gland. 



The spermatophore has hitherto been known from several 



