NEW OBSERVATIONS ON THE ABERRANT 

 MEDUSA TETRAPLATIA VOLITANS BUSCH 



By William J. Rees and Ernest White 



British Museum (Natural History) 



(Figs. 1-7) 



INTRODUCTION 



THE published records of the occurrence of the aberrant medusa Tetraplatia volitans Busch indicate 

 that it probably has a cosmopolitan distribution, for it has been found sporadically in all oceans. 

 Until now, however, there were no records of its occurrence in the North Atlantic, except south of 

 Gibraltar and in the Mediterranean. Additional material has come to light which extends its known 

 range northwards along the edge of the continental shelf off the western seaboard of the British Isles. 

 Farther afield too, there are new records of distribution. 



Recently and independently, two papers have been published on the occurrence of this medusa in 

 different parts of the world (Beyer, 1955 ; Hand, 1955), which to some extent present diverging views 

 on the biology of the species. The object of this paper is, therefore, to draw attention to the fact that 

 this species may be found during deep-sea investigations to the south and west of the British Isles, 

 and to draw some conclusions regarding the biology of the species from the additional data. 



ACKNOWLEDGEMENTS 



We wish to thank Dr N. A. Mackintosh, C.B.E., Dr Helene Bargmann and Mr A. de C. Baker of the 

 National Institute of Oceanography for material in the Discovery collections, and Dr J. H. Eraser, 

 Scottish Home Department, Aberdeen, for a specimen from plankton collected by F.R.V. 'Explorer'. 



NEW RECORDS OF TETRAPLATIA 



The following records of Tetraplatia are based on material taken by Dr G. H. Fowler's cruise to the 

 Bay of Biscay in H.M.S. 'Research' in 1900, by R.R.S. 'Discovery IF, by 'Carnegie VII' and by 

 'Explorer'. 



The records without an asterisk are new, those denoted by an asterisk have been briefly mentioned 

 by Beyer (1955) and those denoted by an obelus are known only as records in the plankton analysis 

 sheets of the Discovery Investigations. 



List of Stations at which Tetraplatia was taken : 



H.M.S. 'Research', July 1900. Approx. 47° N., 7° W., Bay of Biscay 



St. 320, 75-0 fm., 2 specimens. 

 St. 33 <f, loo-o fm., I specimen. 

 St. 356, lOO-o fm., I specimen. 



R.R.S. 'Discovery 11' 



St. 670, 44° 52' S., 30° 17' W., South Atlantic, 23. iv. 31, TYFB, 470-0 m. i specimen. 



St. 943, 45° 28-4' S., 179° 06-4' E., South Pacific, S.E. of New Zealand, i. ix. 32, N 70 V, 500-250 m., i specimen. 



*St. 1773, 39° 07' S., 00° 15-5' E.-39° 04' S., 00° 12-5' E., South Atlantic, 24. v. 36, N 70 V, 750-500 m., i specimen. 



