128 



MR. W. L. SCLATER ON A NEW 



[Feb. 16, 



On a new Madreporarian Coral of the Genus Stephanotro- 

 chus from the British Seas, with Notes on its Anatomy. 

 By W. L. ScLATBR, B.A., F.Z.S., Assistant to the 

 Jodrell Professor of Zoology, University College^ London. 



[Received February 15, 1886.] 

 (Plates XII.-XIV.) 



I. Introductory reiuarks, p. 128. 



n. Description of the CoraUum, 



p. 128. 



III. Comparison of S. mosclei/anus 



with other species of the 



genus, p. 130. 



IV. Distribution of the genus Ste- 

 2>hanotrochus, p. 132. 

 V. Anatomy of 8. moseleyanus, 

 p. 132. 

 VI. List of publications on the sub- 

 ject, p. 135. 



I. Introductory. 



Professor Moseley has kindly placed in my hands for e.\amination 

 and description a specimen of a Madreporarian coral, which I have 

 now the pleasm-e of exhibiting to the Society. The coral is of much 

 interest, as being the finest and largest of the i^enus Stephanotrochus, 

 lately instituted by Professor Moseley (1)' ('Challenger' Report on 

 Corals, p. 151), and also as being the first e.xample 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. S" 18' W.; depth 5/0 fathoms ; 

 bottom, ooze ; bottom temperature, 45°*7 F. (7°"7C.). 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 CoraUum. 



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 ; 



^ The numbers refer to the List of Publications at the end of the paper. 



