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Show 1 9 0 6 . ] TURBELLARIA OF THE CAPE VERDE ISLANDS, 7 0 9 The eye-spots have the arrangement which is typical for the genus. There are a pair of tentacle eye-groups, one on either side of the brain, each consisting of four or five large eye-spots. In front of these on either side are a very few (seven or eight) smaller eyes. The musculature of the dorsal body-wall is unusually well developed, especially the oblique inner layer. The dorsi-ventral fibres also are unusually abundant and of large size. The short blunt muscular penis projects downwards and a little backwards into the antrum masculinum. It has no stylet. From it the muscular ductus ejaculatorius runs forward, rapidly widening to form a prostatic compartment whose walls are lined with a secretory epithelium, but are not chambered. From the anterior end of this chamber the duct runs forward again as a narrow muscular tube, again soon widening to form a vesicula seminalis, which receives at its anterior end the vasa deferentia. The prostate and vesicle are not so clearly segmented off from each other as in most species of Leptoplana; in fact with the conducting part they form a nearly straight tube whose walls, surrounded throughout their entire length by circular muscle-fibres, vary somewhat in thickness; being thickest in those parts of the tube where the lumen is greatest, that is to say in the prostate and in the vesicula seminalis. The antrum femininum, opening close behind the antrum masculinum, passes dorsally into a narrow duct which receives the secretions of the shell-glands, and then, turning backwards, opens after a short course into a large accessory vesicle lined with a vacuolated secretory epithelium. This vesicle contains in the present specimen a quantity of spermatozoa. Just before it opens into the accessory vesicle the vaginal duct is joined on its ventral side by the common termination of the uteri. The shell-glands are very large, disposed in a dorsal and ventral layer on either side of the middle line, converging on the sides of the vagina. They extend outward to the margins of the body. Leptoplana graffii may be defined as a Leptoplana with a very elongated body. Penis icithout a stylet; prostate unchambered, moderately distinct. Antrum femininum non-muscular ; a large spherical accessory vesicle present. Z yg an tr o p l an a , gen. nov. Z yg a n tr o p l a n a v e r r il l i , sp. n. (Plate LII. figs. 1 & 2.) Two specimens. St. Vincent Harbour. (6.) " Amongst weed collected by a diver in 1 or 2 fathoms. " Oval with a much waved margin. General colour brown, with broad, nearly colourless margin, the edge itself with a light red-brown tinge. Under side colourless." Length 7 mm. ; breadth 4 mm. The eye-spots are arranged in two rows convex inwards, lying at the sides and in front of the level of the brain. This organ is |