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“On Saturday, the 3d, we sounded in 1240 fathoms and low­ered the dredge, which again gave us a very full sample of the fauna. Star-fishes allied to the genus Archaster were once more most prominent, and among these were several specimens of a very beautiful little sea-star, which I propose to name Por­cellanaster ceruleus, most nearly allied to Ctenodiscus, but pre­senting many marked differences. The disk in a full-sized ex­ample is about 20 mm. in diameter, and the length of the arms nearly equals the diameter of the disk. The ad-ambulacral plates are large, and each bears usually two flattened somewhat irregularly shaped spines. Those plates forming the angles of the mouth are unusually flattened and expanded. The mar­ginal plates are of large size and arranged in two rows. The surface is finely granular and each plate of the upper series bears near its inner edge a rounded tubercle. The two terminal marginal plates on each arm are fused together, and bear two diverging spines, one on either side, and above these on the dorsal aspect a central spine set on a low tubercle. In the re-entering angles between the arms the two central pairs of marginal plates are closely covered with minute flattened scales inserted on edge, and arranged in vertical rows. This is a most characteristic style of ornament; it looks as if there were a little brush between each pair of arms. The perisom of the dorsal surface is loaded with narrow calcareous plates which run together toward the ends of the arms so as to form an almost continuous calcareous investment; paxillae are scattered over the disk, and the outer layer of the perisom of the disk has a very delicate color, ranging from a pale to a tolerably strong cobalt-blue. The calcareous plates are clear white, with somewhat of a porcellanous lustre, and look harder than the surface plates usually do in star-fishes. The madreporic tuber­cle is large, with sub-parallel grooves and ridges; the excretory opening is very distinct in the centre of the dorsal perisom of the disk. This is a very widely distributed deep-water species. We met with it near Tristan d'Acunlia, in the Southern Sea, and in the North Pacific. There is an allied species of the same genus somewhat more ornate, and of an orange instead of a blue color, in the China Sea.”



(Thomson, 1878: 351-353)


Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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