Japanese Freshwater Triclads. 31 



Stoppenbrink, Micoletzky, Burr and others, the tuba of the ovi- 

 duct appears to have function in connexion with the seminal 

 receptacle, though Burr expounds that "Den Tricladen fehlt 

 eben dann das, was man bei anderen Würmern ReceptacuUmi 

 seminis nennt." Tu this I am inclined to apply the name acces- 

 sory or secondary seminal receptacle, in which the union of the 

 sexual elements takes place. 



The occurrence of the egg- and yolk-cells together with tlie 

 spermatozoa in the cavity of the so-called uterus has been placed 

 on record Ijy some previous authorities, who mostly assumed the 

 formation of the cocoon in that organ, ascribing the source of the 

 capsule to its glandular wall. According to some investigators, 

 however, the formation of the cocoon certainly takes place in the 

 genital , atrium. As stated by Burr, the cocoon capsule seems to 

 be composed of minute granules, originating from the 3^olk-cells, 

 as well as (jf the fluid ground substance, coming from the ery- 

 throphil shell-glands. With regard to the formation of the cocoon 

 however, I have no observation to put forward. Upon the 

 entrance of such elements as the spermatozoa, egg- and yolk- 

 cells into the organ Oscar Schmidt (64) assumed that the opening 

 of the oviduct comes into direct communication with the stalk of 

 the uterus, and then the elements appear to finally make their 

 way to the organ Ijy means of the peristaltic movement. Von 

 Kennel Avas of the opinion that these may enter the uterus, owing 

 to the remarkal)le contraction which frequently occurs in tlie 

 region of the genital apparatus during preservation; while lUriiR 

 said " dass ein normaler Aufenthalt der Eier und Dotterzellen in 

 Uterus überhaupt nicht erklärt werden könnte." To my mind, 

 however, the elements seem to reach the lumen of the uterus, due 

 to the contraction of the worm-body during preservation. 



JPlauarin pellncitfa Ij. et Kab. 



This species occurs beneath stones and fallen leaves in a cold 

 running stream in tlie wooded hills to the east of Toyohara 

 (Vladimirofka), Saghalin. Some specimens were procured by 



