42 



Art. 9.— M. Teri and T. Kaburaki 



43 



28. Prosthiosl otttte tu gratifie Stimpson. 



(PI. IL, fig. 2.— Textfigs. 43, 44). 



Prosthiostomim grande, Stimpson 1857, pp. 4, 10. 

 Leptoplana grande, Diesing 18G2, p. 539. 

 ? ProsthioUomum affine, Stimpson, pp. 4, 10. 

 Lejitoplana aflïnis, Diesing 1862, p. 539. 

 Prosthiostomum grande, Lang 1884, p. 603. 



With Stimpson' s Prosthiostomum grande from " Ousima " we 

 identify the numerous specimens which were collected at Misaki, 

 Matsuwa and Mera. They were found adhering to the underside 

 of stones and shells near the low-tide mark. 



The body is of an oblong shape, rounded at both ends, though 

 somewhat more broadly anteriorly than posteriorly. It may 

 measure 22 mm. in length and 5 mm. in breadth. The texture is 

 very delicate. 



The translucent body presents a light 

 buffy ground colour. There exists a dark- 

 looking median zone, inclosing a light 

 buffy space in front of the middle. Fairly 

 uniformly distributed all over the dorsal 

 surface are numerous small spots of an 

 ochraceous colour. 



Cerebral eye-spots in two crowded 

 groups; marginal eye-spots about 25 in number, forming two 

 irregular rows along the frontal margin (textfig. 43). 



Sucker nearly in the centre of 

 the ventral surface. Mouth situated 

 near the brain and at the anterior 

 end of the pharyngeal sheath, which 

 extends through a great part of the 

 median zone in the anterior half of 

 body. 



Genital apertures closely behind 

 pharyngeal sheath. End-organs of 

 genital systems essentially similar to 

 those of the preceding species and 

 quite as were described by Lang in 



Textfig. 43. Eyc-.spots of 

 Prosthiostomum grande. 



Textfig. 44. Diagrammatic representa- 

 tion of the male genital end-organs 

 of P. grande, as seen from the ventral 

 side. 

 Index letters as in textfig-. 4. 



