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Show 256 SIR CHARLES ELIOT ON NUDIBRANCHS [Mar. 1 7, vivid crimson-lake. The body of the rhinophores is brown and inconspicuous, but the tips are whitish and have a crimson ring. Although the colour of the animal when analysed is as described, the general effect in most lights is that it is purple with a silvery glaze. The specimens were active in their movements, and in particular the long oral tentacles were very mobile. The anterior margin of the foot was produced into two deeply-grooved processes, and its sides projected in two laminae along the whole length of the body. The cerata, which were not at all caducous, were set on fan-like projections of the dorsal margin, from 13 to 20 in number, on each of which were from 10 to 20 cerata. The largest individual appeared to have about 640 cerata in all. None of the cerata were large, but they became more crowded and smaller towards the end of the body, where they extended to the tip of the tail. In three of the preserved specimens there was a very distinct raised border on each side of the back, connecting the fan-like projections, and almost resembling the mantle-edge of Dorids; but in the fourth this remarkable character was not visible. The oral tentacles were very large and long; the rhinophores, which stand between the first clumps of cerata, were small and lamellated, except the tips, which were narrow and smooth. In the individual dissected the radula consisted of a single series of 18 yellowish teeth. The separate teeth were much as represented in Bergli's plate (I. c. pi. iii. figs. 5, 6, 7), but somewhat more regular in shape, having nine denticles very symmetrically arranged on each side of a central cusp, but not taking the form of indentations of the cusp itself. The cutting-edge of the jaw bore a row of fine but very distinct denticles, at the side of which were several rows of less distinct accessory denticles. No spine or other armature was discovered in the reproductive system. These specimens seem to clearly belong to Bergh's genus Pteraeo-lidia. There are some small differences (such as the shape of the rhinophores and of the teeth and the lateral ridges) between them and his description and plates of Pteraeolidia (Flabellina) semperiy but the ridges were absent in one specimen and the other characters were slight. It is possible, however, that a comparison of the living animals might show a specific difference. E rco lan ia z a n z ib a r ic a , n. sp. (For the genus Ercolania see Trinchese, " Un nuovo genere della fam. degli Eolididei," Ann. del Mus. di Stor. Nat. di Genova, ii. 1872; id. " Aeolidsedel Porto di Genova" ; Bergh, Beitr. z. Kennt. der Aeolidiaden, v. pp. 9-18, Wien, 1878; Vayssiere, Recherches sur Moll. Opisthobranches, Marseilles, 1888, pp. 121-128.) Two specimens captured at Chuaka, East Coast of Zanzibar, in February 1901. The living animal was rather more than 2 centimetres long, very fragile and delicate, transparent and of a uniform bright green, the hepatic diverticula in the cerata not |
