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Show 92 SIR C. ELIOT ON NUDIBRANCHS [May 17, perfoliations. As in the last species, the gills are very thick, strong, and muscular, apparently five, but in this case, too, the lateral pairs sometimes coalesce, so that the whole number may be counted as three or four. They are bipinnate. The oral tentacles appear as large, distinct tubercles on each side of the mouth, and were doubtless fairly long in life. The foot is rather broad, with a shallow groove in front; the upper lamina is connected with the sides of the mouth under the tentacles. The internal organs are mostly of a greyish yellow, not deep black as in the last species. Though the labial cuticle contained a few scattered yellowish rods, no connected armature is visible. The radula much resembles that of N. cristata, and has for formula about 27 X 10+1.1.1 + 10 or occasionally 11 + 1.1.1 + 11, but the median plate is broader, with five distinct denticulations which do not vary in number. The first lateral has a groove near the end of the hook, and the next two or three teeth have a rudimentary hamate shape. The liver is large. The upper wall of the pericardium is very thick and strong. The verge resembles the figures in Bergh's plates of Nembrotha nigerrirna, the glans being armed with a profuse mass of hamate teeth. Those on the top seemed rather larger and more curved than in his figures. This species is closely allied to N. nigerrirna, but appears to be sufficiently distinguished by (a) its coloration, (b) the only slightly projecting edges of the rhinopliore-pockets, (c) the absence of a labial armature, (d) slight differences in the radula, (e) another form of tentacles. N embro th a a f f in is , sp. n. (Plate IY . figs. 3a-3d.) [Of. iV. gratiosa Bergh, Nudibr. of ‘Blake' Expedition, pp. 172- 175.] One specimen caught in a trawl in Ohuaka Bay on the East Coast of Zanzibar. Yery long and narrow, being 5 centimetres in length and 1 in height. The living animal was extremely soft, dull violet-black in colour, with dull yellow stripes on the sides and somewhat brighter ones of the same colour on the back. The stems and bases of the gills were light green, and the same colour occurred between the rhinophores and round the edges of their pockets. The pinnae of the gills looked black, but when seen by transmitted light were of a fine purple. The foot was very narrow, and the animal could not adhere strongly to anything. The alcoholic specimen is flabby, 28 millimetres long, 5 broad, and 10 high. As the result of this reduction in size, the yellow parts look wider and the black parts narrower, so that the animal appears to be yellow with black stripes, rather than black with yellow stripes as in Mr. Crossland's figure. No doubt, however, the latter is correct; it represents four lateral yellow stripes and one medio-dorsal. The stripes are interrupted in places, particularly on the tail, and there are some long yellow spots between them. The branchiae are distinctly only three in number, smaller |