2 Laidlaw, Polyclad Tuj'bellaria in the British Museiwi. 



STYLOCHID^E. 



Stylochin.^. 



Genital openings close to each other and to the hinder 

 end of the body. Penis without stylet. Tentacles and 

 marginal eyes present. The prostate frequently has its 

 walls strongly folded. [:03 a.] 

 Stylochus vigilax, sp. n. 



"Beach. Thursday Id. H.M.S. 'Alert,' 26-10-81." 

 One specimen. 



Length about 35 mm. Breadth 22 mm. 



A Stylochus with marginal eyes on the anterior part 

 of the margin only. Ovaries dorsal, genital openings 

 separated but very close to each other, about 015 mm. 

 apart and about 4 mm. from the hinder end of the body. 

 A peculiarity of this species is the complete absence of 

 any muscular vesicula seminalis. Where the two vasa 

 deferentia unite there is a feeble dilatation but its walls 

 are no more muscular than those of the vasa deferentia 

 themselves. 



vs- 



•^ 



Fig. I. 

 Stylochus vigilax x 4. 



The cluster of eye-spots at the base of either tentacle 

 is rather denser than in most species of the genus. These 



