OCR Text |
Show 1881.] PROF. F. J. BELL ON THE GENUS ASTERIAS. 513 General coloration (after at least twenty-five years' immersion in spirit) white, the suckers yellowish. 22 = 41, /*= 13. Arms 13*5 millim. broad at base, 3 millim. at tip of arm. ASTERIAS VERRILLI, n. sp. (Plate XLVII. figs. 3, 3a.) General formula latr. Arms five, stout; disk large ; ambulacral grooves very wide, adambulacral spines in a single row, madreporic plate anechinoplacid, and almost exactly midway between the centre and the margin of the disk, small and obscure; typacanthid spines on abactinal surface rare, irregular, short, stout, with knobbed ends, more numerous in younger specimens. Respiratory papulae numerous, and in the adult arranged in distinct groups. Clumps of two, three, or four spines, proportionally longer in the young forms, occupy the margins of the actinal surface of the arms; they are longest and most distinct nearest the disk. The side is separated from the dorsal surface of the arm by a somewhat obscure and not closely packed row of short stout spines. 22 = 48, z*=16 .*. B=3r; breadth of arms at base=14 millim., near tip 4*5 millim.; B = 28*5, /*= 7'5, or 22 = 3*8/-. If the specimens have been correctly referred to one species, the spines on the dorsal surface are rather more distinct in the smaller forms, the row of spines running along the upper edge of the side of the arm is more distinct, and the general appearance of the specimens is somewhat different, owing to the greater length and number of the spines on them. The largest specimen, which has been for about forty years in spirit, and the companion specimen are of a brownish coloration. They were collected by the " Antarctic Expedition" in St. Martin's Cove; the three smaller specimens, which were presented to the Museum in 1868, were collected by Dr. Cunningham in " Peckett Harbour and Gregory Bay," and off Elizabeth Island, and are cream-white. ASTERIAS SPIRABILIS, n. sp. (Plate XLVIII. fig. 4.) This species, which was collected in 1842 off the Falkland Islands, is remarkable for the very great development of the membranous respiratory processes. General formula latr. Arms five, rather long, thick, tapering regularly, not wide at the base ; disk comparatively small. Adambulacral spines in a single row; madreporic plate small, obscure, about midway between the centre and the edge of the disk. The whole of the abactinal surface and the sides of the rays are quite soft, owing to the great development of the membranous papulae, which completely cover the disk and arms and almost totally obscure the tubercles of the back. The rather closely packed, not specially stout, adambulacral spines are separated from those that lie beyond them by a fringing line of large respiratory processes. The sides of the actinal surface are |