12 Art. 2.— T. Kaburaki : 



no nuclei. The nucleus containing parts of the epithelium are 

 placed at the outer side of the muscular layers, which con^e 

 directl}' beneath the layer mentioned. 



The seminal receptacle is a large sack-like oi'gan. lying he- 

 tween the penis and the pliaryngeal chamber. Its wall is, as 

 usual, an epithelium made up of columnar cells of a glandular 

 nature, resting on a basement memijrane, outside which are thin 

 muscular layers. 



At the postero-superior aspect the receptacle gives rise to the 

 slender vaginal canal, which, after traversing behind close under 

 the dorsal budy wall, takes a downward course and l;)ends forwards 

 at the end to join the atrium from l)ehind. Internally the canal 

 is hned witli a single epithelium, external to wliich are found 

 circular and longitudinal muscular layers. 



PItniaria f/onovep/iaia DuGÈs^ 



(PI. I, ti-s. 3-6.-Text tig. 5.) 



Synonymy : Planaria gonoccpliala, Duges (22). 



Dugefia gonocephaloides, GirArd (30). 

 Planaria gnnocephaloiiles, Stimpson (75). 



This species, wliich is well kiiown from Europe and North 

 America, is also the commonest and the most widel}^ distributed 

 freshwater planarian in Japanese ten-itories. It is usually found 

 beneath stones and other sunken objects in running and standing- 

 waters in vai'ious regions. 



Form and Dimension. — The head in the living state is, as usual, 

 of a triangular shape with a prominent lappet on either side, tlie 

 sides forming in front a somewhat rounded median angle of ap- 

 proximately 60''. The bod}' is l)roadest at the cephalic lappets. There 

 thus exists behind the head a somewhat neck-like narrowing. 

 The trunk is elongate, slender, with lateral margins even and 

 nearly parallel for a large part of the length, but in the hind parts 

 gradually tapering to a bluntly pointed posterior extremity. The 

 worms commonly measure 20-33 mm. long l)y 2-5-4 mm. broad 



