| OCR Text |
Show 106 MR. F. F. LAIDLAW ON POLYCLADS [May 26, The anatomy of the genital organs is practically identical that of S. neapolitanus [1]. As in that species, the mature ovaries have passed to a ventral position. Text-fig. 5. Anterior end of Stylochus zanzibaricus, sp. nov., showing the arrangement of the eye-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 Stylochus 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; irregularly 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 |
