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Show 1899.] ASTRcEID CORALS FROM THE SOUTH PACIFIC. 759 specimen agrees closely with the form described by Milne-Edwards and Haime under the name of P. profundicella. A third specimen (c) conforms closely over the greater part of its surface with Dana's figures and descriptions of P. virens, with which the polyps of all agree in colour. The young calices, however, and those situated near the edges of the colony are precisely similar to calices in the same situation in specimen (a). From the above it would appear that P. profundicella and P. virens can only be synonyms for different facies of P. abdita. It would also seem probable that several other species, described by various authors, are likewise synonyms. Rotuma ; crest of reef. 2. PRIONASTRCEA FUSCO-VIRIDIS Q. & G. (Plate XL VII. fig. 5.) Astrcea fusco-viridis, Quoy & Gaimard, Voy. de l'Astrol. iv. pl. xvii. fig. 8 (1833). Astrcea fusco-viridis, Dana, Zooph. p. 229, pl. xi. fig. 7 (1848). Prionastrcea fusco-viridis, Milne-Edwards & Haime, Cor. ii. p. 523 (1857). ' I have referred two incrusting masses to this species because the polyps agree absolutely in colour with the above descriptions. The species, too, has priority over the species described by Ehrenberg, Milne-Edwards & Haime, and Dana, with several of which the corallum conforms equally well so far as the descriptions and figures go. The peristome of the polyps is of a bright green colour, round which the external body-wall forms a broad brown ring. The calices vary in shape and depth in different parts of the corallum, but the dividing walls are always relatively thick, compact, and triangular in section. Tbe septa are continuous from calice to calice, and are from *5-l m m . exsert. They vary in number, in the largest calices (1*4 cm. in diameter) often as many as 70 being counted, of which about 25 are subequal in size and fuse with the columella. These alternate with a similar number, which project about half as far, and then there are a number of very narrow septa, in calices of about 1 cm. diameter, scarcely recognizable. All the septa except the smallest are very thin, regular, and equally exsert. Their edges are covered with small, subequal, bluntly angular teeth, usually very close-set, and never have a ragged appearance. In some of the shallower, thicker-walled calices the teeth are often broader, and the section may have an almost precisely similar appearance to that given by Dana in pl. xi. fig. 7 c. The columella is usually well marked and compact, being formed by an anastomosing mass of thin trabeculae, generally ending above in fine papillae. Rotuma ; the species is very common, living on the extreme breaking edge of the reef. Similarly coloured species to this and P. abdita were also very common in the same position on the reefs of Wakaya, Fiji. 49* |