270 



DISCOVERY REPORTS 



Much has been written about the bipolarity of pelagic animals. Prof. D'Arcy Thomp- 

 son^, in his paper on "Marine Faunas" (p. 348), shows that the bipolar hypothesis may 

 be rejected in the case of the Tunicata, Holothurians, Crustacea and fish. As regards 

 the Pteropods, Cleodora sulcata (Pfefl^er) and Clione antarctica, E. A. Smith, seem to be 

 closely allied to, but specifically distinct from, Cleodora pyramidata (L.) and Clione 

 limacina, Fhipps. Limaci/ia helicina, Phipps, on the other hand, is distributed at both poles. 



Some writers have thought that the more archaic species might be expected to exist 

 near the poles, while others have suggested that the more original forms would be found 

 in the warmer regions of the ocean. It seems probable that Chun's theory, that in the 

 case of pelagic animals the deep-sea fauna contains the most primitive types, is right. 

 Bonnevie has shown that three deep-water species, namely Peraclis diversa, Montero- 

 sato, Limacina helicoides, Jeff., and Cleodora falcata,V{e{ier, all exhibit archaic characters. 

 These are all represented in the present collection: Peraclis diversa, Monterosato was 

 taken north of the equator at 0-800 m. and at 2500-2700 m. L. helicoides occurred 

 north-east of the Falkland Islands, off Tristan da Cunha and in three hauls west of the 

 Cape of Good Hope: the nets were fished at 600-2500 m. Cleodora falcata , Pfeffer, 

 was taken north-east of the Falkland Islands in soundings of 1050-1350 (-0) m. 



I wish to express my thanks to Dr Kemp and the Discovery Committee for allowing 

 me to work out this collection, to Miss Barnes of the Dublin Museum, and lastly to 

 Madame Pruvot-Fol, who spared time to give me valuable help on several points and 

 whose drawings of the radula and jaws of the rare Spongiobranchaea intermedia, Pruvot- 

 Fol, are included in this Report. 



LIST OF STATIONS 



The following table gives the positions and other data of the stations to which refer- 

 ence is made in the text. Stations made by R.R.S. ' Discovery ' have no letters prefixed 

 to the numbers ; those of the R.R.S. ' William Scoresby ' have the prefix WS ; and those 

 made from the S.S. 'Anglo-Norse' have the prefix SS denoting 'South Sandwich.' 



Sounding 



^ Proc. Roy. Sue. Edinburgh, 1898. 



