72 



DISCOVERY REPORTS 



Family Philinidae 



The cosmopolitan genus Philine is represented by four species : kerguelensis extends via the Atlantic- 

 Indian Ocean cross-ridge from Kerguelen Island to north of the Falklands, alata from the Palmer 

 Archipelago to the Davis Sea, gibba appears to be restricted to South Georgia and falklandica to the 

 vicinity of the Falklands. 



Family Scaphandridae 



If my reference of a new South Georgian species to Kaitoa is correct, then this link with a Miocene 

 New Zealand genus is of interest. 



Family Siphonariidae 



The characteristic subantarctic genus Kergnelenella ranges from the Magellan Province to South 

 Georgia and eastwards to Kerguelen, the Macquarie Islands, and the subantarctic islands and Stewart 

 Island of New Zealand. The genus shows relationship with the North Pacific boreal Liriola, but 

 connecting links are no longer apparent. 



SUMMARY 



The above discussion shows that it is reasonable to suppose that the bulk of the southern high- 

 latitude molluscan fauna could have been derived from the Americas, particularly the western coast- 

 line, which links more than two-thirds of the structural margin of the Pacific. Southern and eastern 

 dispersal has been assisted by the continuity of the Americas in the Scotia Arc, which reaches the 

 Antarctic Continent at Graham Land and in the Atlantic-Indian Ocean cross-ridge, which runs from 

 the Argentine Basin almost to the Kerguelen-Gaussberg (radial) ridge. Possibly other radial extensions 

 from Antarctica in former times may have operated also in distributing southern fauna to the Australian 

 and New Zealand areas. The subantarctic cross-ridges may also have been much shallower during 

 some former period than at the present time and thus more effective in distributing organisms more or 

 less restricted to the Continental Shelf. 



The prevailing West Wind Drift north of the Antarctic Circle and the opposite East Wind Drift to 

 its south are present factors which must greatly facilitate the lateral distribution of many species. 



With the exception of the Struthiolariidae, which have an ancestry extending back to the Cretaceous, 

 the present southern high-latitude molluscan fauna presents no indication of antiquity. The bulk of the 

 fauna probably results from a series of comparatively recent immigrations during Tertiary to Pleistocene 

 times. There is a marked absence of archaic types such as Pleurotomaria. 



INDEX TO THE DISCOVERY INVESTIGATIONS MOLLUSCA 



(New species*, new genera f) 

 The report covers 215 species and includes descriptions of a new subfamily, the Solariellinae, 26 new 

 genera and subgenera, and 46 new species and subspecies. 



The material, including the types, will be deposited in the British Museum (Natural History). 



PELECYPODA 



Propeleda longicaudata (Thiele, 191 2). Bellingshausen Sea . 



Limopsis hirtella Rochebrune & Mabille, 1889. North of Falkland Is. . 



Limopsis (Felicia) jousseaumi (Rochebrune & Mabille, 1889). Graham Land . 



Lissarca cf. notorcadensis Melvill & Standen, 1907. Falkland Is. to Patagonia 



Pandora (Kennerlia) braziliensis Sowerby, 18746. Patagonia 



Hiatella antarctica (Philippi, 1845). Falkland Is. and Patagonia . 



page 



77 

 77 

 78 

 78 

 79 

 79 



