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Show 128 MR. W. L. SCLATER ON A NEW [Feb. 16, O n a new Madreporarian Coral of the Genus Stephanotro-chus from the British Seas, with Notes on its Anatomy. B y W . L. S C L A T E R , B.A., F.Z.S., Assistant to the Jodrell Professor of Zoology, University College, London. [Eeceived February 15, 1886.] (Plates XII.-XIV.) I. Introductory remarks, p. 128. II. Description of the Corallum, p. 128. III. Comparison of S. moseleyanus with other species of the genus, p. 130. IV. Distribution of the genus Ste-phanotrochus, p. 132. V. Anatomy of S. moseleyanus, p. 132. VI. List of publications on the subject, p. 135. I. Introductory. Professor Moseley has kindly placed in m y hands for examination and description a specimen of a Madreporarian coral, which I have now the pleasure of exhibiting to the Society. The coral is of much interest, as being the finest and largest of the f,enus Stephanotrochus, lately instituted by Professor Moseley (1) 1 ('Challenger' Report on Corals, p. 151), and also as being the first example of this form that has been dredged in British seas. The coral is a solitary form; it was procured on the expedition of H.M.S. 'Triton' in the summer of 1882: "station 13; August 31st, 1882, lat. 59° 51' 2" N., long. 8° 18' W . ; depth 570 fathoms; bottom, ooze; bottom temperature, 45°'7 F. ( 7 ° 7 C ) . Trawl." Station 13 is situated almost in a straight line and about halfway between the Faroe Isles and the northern point of the Hebrides; it lies to the south-west of the Wyville-Thomson ridge, so that it is well within the warm area described by Murray and Tizard (2). The coral is interesting, since it is by far the largest solitary form that has yet been discovered in British seas ; its nearest allies were dredged off the Azores and Pernambuco during the * Challenger ' Expedition. The coral was well preserved in absolute alcohol, so that I have been able to make a fairly satisfactory investigation of its anatomy by means of sections and other microscopical preparations. It is to the kindness of Professor Moseley that I am indebted for this coral; and since the genus and the other four species belonging to it were all described by him in his report on the ' Challenger ' Corals, I propose to dedicate this new British species to him under the name of STEPHANOTROCHUS MOSELEYANUS. II. Description of the Corallum. The corallum is white where covered by the soft tissues; the base is of a bluish-grey colour ; it is saucer-shaped, the base being very nearly flat, but forming a very low cone ; and from this base the side-walls of the theca rise, making an angle of about 60°. In the centre of the base is a very small pedicel of attachment; 1 The numbers refer to the List of Publications at the end of the paper. |