Description of Some Japanese Polyclad Turbellaria. 



43. 



detail. The seminal canals (textfig. 44, so), coming from behind, 

 make an abrupt inward turn slightly behind the penis (p) to enter 

 the seminal vesicle (sv), which gives rise anteriorly to the ejacu- 

 latory duct (ed). This receives at the base of penis the ducts of 

 two small and spherical prostates (pr), one on each side of the 

 ejaculatory duct. Penis small, styliform. 



24. Frosthiostomtiin mar m or ut a in, n. sp. 



(PI. I, fig. 8.— Tcxtfigs. 45, 46). 



A large number of this species were collected between the tide- 

 marks at Shirahama in Prov. Awa. 



Body elongate, anteriorly rounded, nearly uniformly broad for 

 a great part of its length, posteriorly tapering to a point; dorsal 



surface slightly raised in the median parts 

 behind cerebral eyes. In the fully extended 

 state the worm may reach 21 mm. in length 

 and 5 mm. in breadth. 



Dorsal 'surface yellowish buff and marked 

 all over, except at the head end, with 

 irregular brownish blotches, which at times 

 join together in the median parts into two 

 longitudinal dark-brownish bands. 

 Cerebral eye-spots densely grouped in two oval clusters, in a 

 common colourless space of an oval shape. Marginal eye-spots 



confined to the frontal margin, 

 numbering eighteen or there- 

 about (textfig. 45). 



Sucker nearly central. 

 Mou tîi placed close behind 

 brain. Pharyngeal chamber 

 cylindrical, extending from be- 

 hind brain to about the middle 

 of body. Pharynx cylindrical, 

 but with triangular lumen. 



Genital end-organs essen- 

 tially as in the preceding species,. 



Textfig. 45. Eye-spots of 



Prosthiostomum 



marmoratum. 



tr, 



lextfig. 46. Diagrammatic representation of 

 the male genital end-organs of P. mar- 

 moratum, as seen from the ventral side. 

 Index letter? as in textfig. 4. 



