106 MR. F. F. LAIDLAW ON POLYCLADS [May 26, 



The anatomy of the genital organs is practically identical with 

 that of S. neapolitanus [1]. As in that species, the mature 

 ovaries have passed to a ventral position. 



Text-%. 5. 



Anterior end of Sti/locJius zanziharicus, sp. nov., showing the arrangement 



of the ej'e-spots. 



Stylochus suesensis Ehrenb. ? 



Stylochus suesensis Lang. 



A single large specimen from Ras Oswemba, 10 fathoms. 



Length 40 mm. 



Breadth 25 „ 



The specimen is much damaged and the dorsal surface badly 

 broken. 



The marginal eye-spots extend completely round the body. 

 This character is not stated to occur in Ehrenberg's type, but 

 may well have been overlooked. In other respects, size and colour, 

 so far as the latter can be determined, viz. dull yellow mottled 

 with small brown spots on the dorsal side, it agrees. The ovaries 

 are immature and lie among the gut diverticula. Doubtless, 

 when ripe, they would shift ventralwards. The penis is squared 

 at its free end. The prostate is very large and has thick 

 muscular walls. 



The genus iStylochus includes at present a few rather closely 

 related species, most of which have a very similar style of 

 coloration, viz. a ground-colour ranging from dirty white to dull 

 yellow or greyish brown ; irregulai-ly mottled with darker spots 

 or streaks of brown. The tentacles lie far forward and carry 

 eye- spots. Marginal eye-spots may extend completely round 

 the body. 



A satisfactory grouping of the species is not at present possible, 

 since one of the most remarkable features, known to occur 

 in several species, viz. the ventral position of the ovaries, has 



