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Show 1894.] ECHINODERMS OF MACCLESFIELD BANK. 405 sharp spine; the plates that bear such spines are most numerous near the bases of the arms. There are eight fine spines bordering the narrow ambulacral groove, the shortest of which are at the sides, and the whole set of which forms a fan-like expansion ; there follow on these four upright and stouter spines. The arm-plates are covered with fine projecting glassy spines, which, on the disc, are blunt. E = 87-5, r=9-5. Breadth of arm at base 7*5. Height of arm 7*5. Macclesfield Bank, 30-40 fms. If I a m right, which I very much doubt, in assigning this species to the genus Chcetaster, the diagnosis of the genus will have to be so far altered as to include the possible possession by the plates of the arms of central projecting spines. A difference in the combination of circumstances makes it sometimes right, sometimes wrong, to form a new genus or a new species on the evidence afforded by a single specimen ; in the present case I can only briefly give the evidence of the existence of a type hitherto unrecognized. OPHIDIASTER HELICOSTICHUS. Ophidiaster helicostichus, Sladen, Chall. Eep. Ast. xxx. p. 405. Two fine specimens, one from Holothuria Bank (15 fms.) and the other merely reported as from N . W . Australia, are so much larger than the specimens which I have referred to m y Linckia megaloplax, that I cannot assert that they are all members of one species, but I have very little doubt on the point. EHIPIDASTER VANNIPES. Rhipidaster vannipes, Sladen, Chall. Eep. Ast. xxx. p. 448. I am inclined to think that two small specimens, one of which is quite minute, from 32 fms. may, when a fuU series is obtained, be shown to be the young of this species founded on a single specimen, the spread of which is more than 170 millim. Between them at present it seems useless to make a comparison. Both the small specimens have nine arms. ASTERIAS YOLSELLATA. Asterias (Stolasterias) volsellata, Sladen, Chall. Eep. Ast. xxx. p. 584. A small example of this species, the only other known example of which is the one that formed the basis of Mr. Sladen's description, is another of the finds on which Mr. Bassett-Smith is to be congratulated. The whole spread of this new specimen is less than 30 millim., but its Brisinga-like appearance is no more marked than that of the " type." It has unfortunately been in recent years so rare an occurrence for m e to be able to agree with the views of the describer of this species, that I gladly seize the opportunity of saying that he seems P R O C . ZOOL. Soc-1894, No. X X V I I . 27 |