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Show 1903.] FROM EAST AFRICA AND ZANZIBAR. 367 stomach is quite free from the hepatic mass. No armature was discernible in the reproductive organs. I have some hesitation in classifying this specimen as Peltodoris, as the back is not minutely granulated but covered with small warts. The shape, however, is not that of Archidoris, and both the stiffness and small radula are in favour of the position here assigned to the form. 9. THORDISA VILLOSA (A. & H.). (Plate XXXII. figs. 1 & 2 ; Plate XXXIII. figs. 1-3.) [Alder & Hancock, Trans. Zool. Soc. Lond. vol. iii. (1864) p. 119, pi. xxxiii. fig. 1 ; Bergh, Semper's Reisen, Heft xii. (1877) p. 540 ; Bergh, Danish Exped. to Siam, Opisthobranchiata, 1902, p. 182.] One specimen was dredged in Zanzibar Harbour on a sandy bottom with a little Zostera (PI. X X X I I . figs. 1 & 2). The groundcolour of the living animal is a translucent yellew, like a bit of crystallised fruit. On the ample and transparent mantle-margin were blotches of peaty red and of different sizes. Smaller spots of the same colour are scattered over the whole body, particularly above the visceral mass. The under surface is uniform bright yellow with a few brown clots. The whole dorsal surface is covered with colourless transparent papillae (PI. X X X I I I . fig. 2), some simple (especially on the mantle-edge), and some compound with two or more filaments. It is also plentifully supplied with spicules set in a stellate arrangement, but the general consistency is quite soft and not stiff. The rhinophore and branchial openings are slightly raised and tuberculate, but not stellate. The rhinophores are large and slightly bent back; the stalk is rather longer than the laminated portion. The branchiae are six and mostly only bipinnate, though tripinnate branches also occur (PI. X X X I I I . fig. 3). They are grey with a brown rhachis. The foot is grooved in front but not notched. The tentacles are thin and digitate. There is no trace of labial armature. The radula consists of about 47 rows of simply hamate teeth, each row containing 40-50 on either side of the rhachis. They are all of the same shape and size, except the outermost five or six, which bear from seven to ten long fine hair-like denticles on each side of the much reduced central hook. No armature was discoverable in the reproductive system. The alcoholic specimen is quite flat, and is 2-5 centimetres long by 1*6 broad, but the living animal was capable of assuming two shapes-one flat with a broad mantle-edge, and one high with a much narrower edge (PI. X X X I I I . fig. 1). I think this animal may be safely identified with the Doris {Thordisa) villosa of A. & H. Bergh seems to think that this species is probably identical with his Thordisa maculigera, and I share this view, though the formation of the outermost teeth is not exactly like either his description or his plate, as the denticles are longer and the central hook, though much reduced, has not vanished. |
