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Show 430 PROF. J. A. THOMSON AND MR. W. D. HENDERSON ON [Apr. 10, The spicules of the general coenenchyma are all of one type-spindles covered with rough warts, which are arranged in regular whorls, and often blunt at both ends. Some of the spicules are yellowish-amber colour, often almost colourless at the tips ; others are quite colourless. Their measurements, length by breadth in millims., are as follows :- Coloured: 0*2x0*05; 0*12x0*06; 0*16x0*05; 0*16x0*04; 0*14x0*05. Colourless: 0*06x0*03; 0*08x0*04; 0*12x0*05; 0*14x0*05; 0*1x0*04. Loccdity. Wasin Channel, 10 fathoms. (B.)-Another colony forms a thin encrustation on a piece of bivalve shell, about 25 m m . by 30 mm., with nine stems rising at various angles. Three of the stems lie on the under concave surface of the shell and keep close to it; the four longest on the other side extend to 65-80 m m . from the shell. Two have a single branch. The greatest breadth is about 2 m m . There is a slight flattening in the plane in which the polyps for the most part arise. The general colour is a quiet orange. The verruca? are inconspicuous and for the most part lateral; some of them show eight distinct marginal lobes. The polyps are pure white. A longitudinal groove is distinct for a short distance from the base. The spicules are spindles with warts in whorls 0*12x0*04, 0*14x0*04 mm.; and double spindles 0*13x0*06, 0*12x0*05; and a few small almost orbicular forms. This form approaches S. kbllikeri Wright k Studer, but differs from it in the size and prominence of the verruca? and in the size of the spicules, but it is connected to that species by Suberogorgia, kbllikeri, var. ceylonensis. But the Zanzibar form has smaller verruca? and spicules than the Ceylonese variety, and the series may be regarded as illustrating progressive variation. Loccdity. Kokotoni Harbour, Zanzibar West, 5 fathoms. Family MELITODID^E. WRIGHTELLA ERYTHRCEA Gray = MOPSEA ERYTHRCEA Klunzinger. (Plate XXVIII. fig. 10.) Small, irregularly branched, rose-red colonies, fixed to coral. The branches are not always confined to one plane. The following measurements were taken of height and breadth in millims. :- 15x23; 23x8; 15x8. The specimens agree well with Klun-zinger's description of Mopsea erythrcea, e. g. in the presence of a single red spicule at the base of each tentacle and in the dimensions of the spicules generally. Localities. Wasin, low tide, growing on coral; Prison Island, Zanzibar Harbour. Previously recorded from the Red Sea. In the Aberdeen University Museum there is a specimen from Samoa which is superficially identical with these. It is labelled Mopsea erythrcea. |