8 DISCOVERY REPORTS 



some of the stations above 70° S. A long list of species could be compiled. At one of the 

 most southern stations, WS 505 in 70° 10' 30" S, the following species were recorded, 

 all denizens of warmer water: Bolivina cincta, B. deciissata, B. spinescens, Cassidulina 

 subglobosa (very large), Globigerina bulloides, G. diitertrei, Gaiidryina flintii, Lagena 

 laureata, Verneuilina bradyi, V. bradyi var. nitens (not found otherwise except in Drake 

 Strait and Scotia Sea), and Virgulina schreibersiana var. complanata. Hyperammina 

 novae-zealandiae at St. WS 515, and Gaudryina ferniginea at St. WS 516, are in them- 

 selves strong evidence of Pacific influence. The best and largest specimens of Cibicides 

 wuellerstorffi were found at St.WS505, the only other records being in the Drake 

 Strait and Scotia Sea, while Epistomina elegans, known otherwise only from one small 

 specimen at St. WS 469 on the convergence, yielded two very large individuals at 

 St. WS 505, which appears to be its most southern record. 



SOUTH GEORGIA AND ITS ISOLATED FAUNA 



The preparation of a separate report for the Foraminifera of South Georgia was, in its 

 inception, purely a matter of convenience, as the island lies within the Antarctic con- 

 vergence line, and its fauna might have been expected to be similar to that of the 

 regions farther to the south. But the amount of Antarctic material already received, to 

 which additions were continually being made, was so large that it was felt to be impos- 

 sible to deal with it as a whole. It was decided to divide the Antarctic report into two 

 parts, and South Georgia being in itself rather an isolated area, naturally formed a 

 section. The course followed has proved to be fortunate, for South Georgia, instead of 

 being a homogeneous factor with the rest of the Antarctic area, has been found to possess 

 a foraminiferal fauna difl^ering in many respects from that of the adjacent islands. The 

 full extent of this difl^erence had not been realized when I drew attention to its existence 

 on p. 31 of the South Georgia report. 



This difl^erence is no doubt partly due to the peculiar nature of its shallow-water 

 bottom deposits, which generally speaking are tenacious muds of terrigenous origin and 

 loaded with diatoms, thus forming a particularly rich feeding ground for the large mud- 

 eating species. By contrast, the shallow-water deposits of the South Sandwich, South 

 Orkney and South Shetland groups are coarse and sandy, often of volcanic origin, and 

 deposits of mud are infrequent. But it seems probable that current action is more 

 responsible for the distinctive nature of the South Georgian fauna. The island, cut off 

 by deep water from all the adjacent groups, is practically encircled by cold Antarctic 

 water sweeping up from the Weddell and Bellingshausen Seas, while the warmer Pacific 

 water passes to the north of the island, after influencing the fauna of regions farther 

 south. The foraminiferal fauna of South Georgia therefore remains isolated, and to 

 some extent preserves an Antarctic facies which the southern areas are losing. Species 

 of distinctly Pacific origin are very few in comparison with their number in higher 

 latitudes. In its isolation. South Georgia has either preserved or developed species 

 which are almost confined to the island. Thus its most characteristic species, Ehren- 



