30 



Art, 9.— IM. Yeri and T. Kaburaki 



14. JPsentlostylochtts obscurus (StimpsOn). 



(PI. I., fig. 10.— Textfigs. 33, 34). 



Styloeluu obscurus, Stimpson 1857, pp. 4, 11. — Diesing 1802, p. 566.— Lang 1884, 

 p. 464. 



Numerous specimens of what we are inclined to identify with 

 Stimpson's Stylochus obscurus were obtained between the tide- 

 marks at Misaki, at Mera in Prow Awa, and also at Otaru in Hok- 

 kaido. Stimpson gave the sublittoral zone of Hokkaido (" Yesso ") 

 for the habitat of Stylochus obscurus. In our opinion the species 

 should be placed under the new genus Psevdostylochus. 



Body oval or elliptical, moderately firm, and usually measuring 

 20 mm. long by 15 mm. broad. 



Ground colour of dorsal surface deep olive-buffy, dotted all over 

 with minute dark greenish pigments. A darkish median stripe 

 occupies the region of pharynx. Stimpson has given the colour of 

 the species to be bluish gray and blotched with blackish pigment 

 spots. Ventral surface grayish or pale, unpigmented; the lobed 

 pharynx and the reproductive system visible with more or less 

 distinctness in a whitish colour. 



Tentacles small, bluntly conical ; each situated on the posterior 

 border of the first quarter of body. 



Tentacular eye-spots forming 

 a crowded group at the base of 

 each tentacle. Cerebral eye'-spots 

 in an elongate tract on either side 

 of the median line. No eye-spots 

 elsewhere on the body (textfig. 

 33). 



Mouth placed nearly in the 

 centre of the ventral surface. 

 Pharyngeal pocket with some ir- 

 regularly lobed diverticula. Main 

 gut provided with about 10 pairs 

 of lateral intestinal branches which show no sign of anastomosis. 



Genital organs (textfig. 34) are essentially in accord with those 

 of the preceding species. The seminal canals join into a single 



33 



Textfig-. 33. Eye-spots of Pseudostyloehus 



obscurus. 



