DISTRIBUTION OF FORAMINIFERA 19 



and Pearcey records it from the Burdwood Bank. It is found fossil in the Pliocene of 

 California. 



BoUvina decussata, Brady (No. 281), was described from a Challenger station off 

 Juan Fernandez Island in the south Pacific. Cushman records it with some reservations 

 from off Japan. A few typical specimens were found in South Georgia, and single 

 specimens are now recorded from three stations, two being in the Drake Strait outside 

 and just within the convergence, and the third in the far south of the Bellingshausen 

 Sea. This last record seems clear evidence of an inflow of Pacific water into that sea. 



BoUvina spinescens, Cushman (No. 274), is known from several records spread over 

 the Indo-Pacific and south-west and central Pacific regions. It was found in some 

 numbers in the Falklands area but not in South Georgia. Quite typical specimens were 

 found at four stations in the far south of the Bellingshausen Sea. The 'Terra Nova' 

 recorded it from both New Zealand and the Antarctic. 



Virgidina schreibersiana var. complanata, Egger (No. 270), was first recorded from 

 the west coast of Australia, and subsequently from the east coast by Sidebottom. It is 

 possibly distributed over the Indo-Pacific region but has not been separated by authors. 

 It occurs at no less than seventeen stations spread over the whole area of the present 

 report, with depths ranging between 100 and 4344 m. 



I think these few instances are sufficient to prove an extension of the range of species 

 in an eastern direction across the south Pacific. Many other instances will be found in 

 the preceding pages of the report and in the notes on species. 



DISTRIBUTION OF FORAMINIFERA 



It is much easier to provide evidence of such extension of range, or migrations of 

 benthic species, than to explain how they have come about. Yet we have to find some 

 explanation of the presence of these alien organisms in Antarctic waters. Several 

 theories present themselves, none of which is entirely satisfactory; perhaps the solution 

 may be found eventually in a combination of them. 



(i) Geological survival. These warmer water species may be the survivors from a 

 geological time when coast-lines and climate were different, and a warm-water fauna 

 existed right across the south Pacific from the Australian coast. I am no geologist but 

 understand that there is evidence of the former existence of a warm climate in Antarctica. 

 In such case it is quite reasonable to suppose that a few forms might be more adaptable 

 to changes of environment than the majority of their fellows, and survive where other 

 species died out. 



Perhaps the strongest piece of evidence in support of this theory would be the case of 

 Rotalia clathrata, Brady, which is a very common species in shallow water on the coasts 

 of Australia and New Zealand. Geologically it has a history extending back to at least 

 Miocene times in Victoria. It is found to-day on the west coast of Patagonia and in the 

 Falklands (F. 395 and p. 297). But if it was ever domiciled on the Antarctic coast-line 

 it has not adapted itself to polar conditions and has disappeared. 



(2) Movements of Foraminifera. Given the practically unlimited time furnished by 



3-2 



