Echinoderms of the Rockall Trough and adjacent areas I. Crinoidea, Aster oidea and Ophiuroidea J. D. Gage & Margaret Pearson Dunstaffnage Marine Research Laboratory, Scottish Marine Biological Association, P.O. Box 3, Oban, Argyll PA34 4AD Ailsa M. Clark & G. L. J. Paterson Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD P. A. Tyler Department of Oceanography, University College of Swansea, Swansea SA2 8PP Synopsis Four species of crinoid, forty species of sea star and thirty-six species of brittle star are identified from recent benthic sampling in the deep-sea area to the west of the British Isles, mainly in the Rockall Trough. Of these, one crinoid, nine asteroids and eighteen ophiuroids have not previously been recorded from the seas around the British Isles. The zoogeographical distribution and bathymetric range of each species is summarised as far as was previously known giving the range extension provided by the present records. Notes are also provided on observations on the biology, including the mode of reproduction, of the more abundant species. The records demonstrate a broader bathymetric distri-bution of juvenile and post larval stages than of the adult populations of some of the more abundant species. A greater diversity of species also is evident from the small number of samples from the western, probably current-swept, side of the Rockall Trough compared with the much larger number of samples collected at similar depths in the east. Introduction The cruises of H.M.S. Lightning and H.M.S. Porcupine in the years 1868-70 in the Rockall Trough and other deep sea areas lying west of the British Isles and of the Iberian peninsula asserted beyond doubt the presence of life at great depths. Echinoderm data figure prominently in the literature (Lyman, 1882; Sladen, 1889; Thomson, 1872, 1873, 1874) resulting from these cruises that covered deep-sea areas not subsequently sampled by the Challenger expedition of 1872-76. Many useful echinoderm records also were made on the cruises of H.M.S. Knight-Errant in 1880 and H.M.S. Triton in 1882 in the course of exploration of the submarine sill bounding the northern end of the Rockall Trough that was subsequently named the Wyville Thomson Ridge (e.g. Hoyle, 1884; Sladen, 1882). To the authors' knowledge most subsequent records of deep-sea echinoderm fauna from this area have emanated from opportunistic extension into deeper water of essen-tially coastal sampling programmes. Notable among these are the cruises of the Irish Fish-eries Department cruiser Helga in the early years of this century. Exploration of some of the outer banks and shelf areas around the northern perimeter of the Rockall Trough has also resulted in many useful records of fauna including echinoderms (Danielssen & Koren, 1884; Siissbach & Breckner, 1911; Pawsey & Davis, 1924). Other records have come from stations worked in the Rockall area in the course of wider ranging cruises, such as those of the Thor, and the Michael Sars in her Atlantic expedition of 1910, and more recently Bull. Br. Mus. not. Hist. (Zool.) 45(5): 263-308 Issued 29 September 1983 263
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