THE FALKLAND AREA 295 



The number of Foraminifera present in these "Shelf" stations varies enormously, 

 and as the bottom conditions are otherwise very similar, we are inclined to the view that 

 they are influenced very largely by the Falkland Islands current, which no doubt brings 

 with it large food supplies in the shape of diatoms and other micro-plankton. At 

 stations WS 86 and 87 on the Burdwood Bank, and at station WS 88 which is in line with 

 them to the westward, just within the curving southern extremity of the Continent, 

 Foraminifera are abundant and form a large proportion of the bottom deposit. There is 

 a similarly abundant fauna at stations WS 83, 84, 91 , 92, farther north, where the current 

 divides to encircle the islands. But as we get farther away from the entrance point of the 

 current, and especially as we approach the Continental shore, the sand becomes 

 increasingly barren of Foraminifera (stations WS 77, 78, 79, 80, 90, 94, 95, 108) until, 

 at station WS 96, which is near Port Desire, they are practically absent. They reappear 

 in some abundance in the stations to the north of the islands on the edge of the deeper 

 water, near the mud line. 



There is a monotonous sameness in the foraminiferal fauna over the whole of the 

 Shelf area, and on a casual inspection it appears to be almost identical at the majority of 

 stations and to consist of a few species only : 



CassidiiJina crossa Truncatulina lobatida 



CassiduJina subglohosa Truncatidma refulgem 



Cassididina parkeriana Truncatulina akneriana 



Ehrenbergina pupa Tnincatidina ungeriana 



Uvigerina angulosa Anomalina vermiculata 



Globigerina — several species Pulvinulina karsteni 



Pidlenia subcarinata 

 These few species as a rule, in one combination or another, form the bulk of the 

 material with either Cassidulina crassa or Uvigerina angulosa, or the two together, 

 assuming a dominant position, even among what appears to be a very limited fauna. At 

 some of the stations, Cassididina crassa was estimated to form 90-95 per cent of the 

 cleaned material, at others Uvigerina angulosa probably formed an equally high propor- 

 tion. The occurrence of a species in such overwhelming numbers might be expected to 

 produce many abnormalities, and it is therefore worthy of mention that abnormal 

 specimens are extremely rare. 



It is only after the examination of a quantity of material that it becomes apparent that 

 a really varied list of species is present at some of these stations, masked by the dominant 

 forms. Station WS 83 may be quoted as an instance. The material was to all superficial 

 appearances very unpromising, as Cassidulinae formed at least 90 per cent of the mass. 

 But the remaining 10 per cent, proved to be extraordinarily rich and yielded some 200 

 species. The list could doubtless have been extended if time and more material had been 

 available. 



In a few instances, a species which usually occupies a subordinate position becomes 

 almost dominant. As an example we may take Spiroplectammina biformis, a species of 

 very wide distribution in many seas, though never common. It occurs at eleven stations, 



