INTRODUCTION 57 



Regarding the Foraminifera, Earland (1934, p. 8) remarked that 'In its isolation, South Georgia 

 has either preserved or developed species which are almost confined to the island '. 



The molluscan fauna has scarcely any species common to the Falklands. On the other hand, the 

 present collections include a number of genera and species previously considered characteristic of the 

 Kerguelen and the Ross Sea areas. Their significance, however, is partly ecological, in that the blue 

 muds of South Georgia are more comparable with the Ross Sea bottom than they are with the coarse 

 sandy bottom of the shallower areas of much of the Scotia Arc. This would account for the presence in 

 South Georgia of the antarctic species Trichoconcha mirabilis, but its apparent absence from other 

 Scotia Sea localities. 



A physical factor which must have the effect of distributing Ross and Victorian Quadrant species 

 eastward into the Weddell Quadrant is the East Wind Drift which operates contrary to the West Wind 

 Drift at and below 65 S. 



The South Georgian fauna must now be fairly completely known. It is very distinctive, and as 

 already noted has little in common with that of the Falklands, which are almost of the same latitude. 



There are several endemic genera; Venustatrochus, Promargarita, Pfefferia, Chlanidotella and 

 Cavineptiinea. Antarctic genera and species are strongly represented : Patinigera polar is, Laevilacunaria, 

 Trichoconcha, Prosipho, Chlanidota, Probuccinum and Neactaeonina. The widely distributed Antarctic- 

 Subantarctic genera Gaimardia and Margarella are represented almost entirely by endemic species. 



The characteristic Magellanic genera Nacella, Photinula, Photinastoma, Xymenella and Adelomelon 

 are not represented. Evidence, however, that the Scotia Arc was formerly a more effective route than 

 at present for the southward spread of the Magellanic fauna is shown by the presence of a Trochita 

 (georgiana n.sp.) and a derivative of Calliostoma (Venustatrochus georgianus n.gen. and n.sp.). Deep- 

 water severing of the arc has culminated by isolation in the development of the South Georgian fauna 

 as a distinctive unit. 



On the other hand, there is a strong representation of both eastern Subantarctic and Antarctic forms 

 characteristic of the Victoria and Enderby Quadrants : Pellilitorina setosa, Amauropsis (Kerguelenatica) 

 grisea, Perissodonta georgiana, Sinuber, Falsimohnia, Proneptunea, Trichoconcha, Probuccinum and 

 Prosipho hunter i. 



South Georgia Check List 

 PELECYPODA 



Nucula minuscula Pfeffer, 1886 (T.). 



Lissarca miliaris (Philippi, 1845); David, 1934. 



L. rubrofusca Smith, 1875; Martens & Pfeffer, 1886; David, 1934. 



Hochstetteria quadrata (Pfeffer, 1886) (T.). 



H. ungulata (Pfeffer, 1886) (T.). 



Cyamium imitans Pfeffer, 1886; David, 1934. 



C. willii Pfeffer, 1886 (T.) ( = mosthaffi Pfeffer, David, 1934). 



Cyamionema decoration Melvill & Standen, 1914; David, 1934. 



Gaimardia f aba (Pfeffer, 1886) (T.). 



G. nigromarginata (Pfeffer, 1886) (T.). 



G. subquadrata (Pfeffer, 1886) (T.). 



G. trapesina (Lamarck, 1822); Martens & Pfeffer, 1886. 



Kidderia bicolor (Martens, 1885) (T.); David, 1934. 



Mysella charcoti (Lamy, 1906); David, 1934. 



'Lepton' costulatum Martens, 1885 (T.). 



'Lyonsia' arcaeformis Martens, 1885 (T.). 



Hiatella antarctica (Philippi, 1845); Martens & Pfeffer, 1886; David, 1934. 



Laternula elliptica (King & Broderip, 1832); David, 1934. 



