FORAMINIFERA 93 



DISTRIBUTION OF ZOOPLANKTON 



PROTOZOA 



The Protozoa recorded fall into one or other of the three groups: Foraminifera, 

 Radiolaria and Tintinnidae. It was not possible in the time available for the analysis of 

 the large number of samples to carry out specific identification of the Protozoa, and the 

 members of the three groups have simply been recorded as such, with the exception of 

 certain of the Radiolaria, which have been grouped according to the genera or families 

 to which they belong. Whilst it is realized that the results in this form can be of little 

 value, they are included in the present report to give an indication of the relative 

 strength of the three groups in the plankton samples from the different regions under 

 consideration. 



Foraminifera 



Mr Heron-Allen and Mr Earland, who have been engaged on systematic reports 



on the Foraminifera, have kindly informed us that the following planktonic species are 



included amongst those collected: 



Glubigerina conglomerata, Schwager. G. pachyderma (Ehrenberg). 



G. bulloides, d'Orbigny. G. triloba, Reuss. 



G. dutertrei, d'Orbigny. Globorotalia {Pulvinulina) scitula (Brady). 



Here we can only deal with the distribution of the Foraminifera in general, as a group. 



On approaching South Georgia from Tristan da Cunha in February 1926, very few 

 were met with; these occurred in the top 100 m. at St. 10 north of the Antarctic Con- 

 vergence; in the top 50 m. at St. 11 just south of the Antarctic Convergence and from 

 500 to 100 m. at St. 12 in the Antarctic Zone, i.e. in water just below the cold Antarctic 

 surface layer where this water is mixing with the warmer intermediate layer below. 



In the December- January survey round South Georgia 1926-7 they were taken in 

 considerable numbers (Fig. 42), being distributed more or less equally to the east, west 

 and south, and in smaller numbers to the north. They occurred in larger numbers over 

 deep water away from the coast, and the greatest numbers were taken at depths between 

 250 and 50 m., although at some stations they occurred in fair numbers in the cold 

 surface layer (see Fig. 43). They also extended down into the zone of pure warm 

 intermediate water. In November 1926 the numbers on the C line were not markedly 

 different from those of December, whilst in the following May, Fig. 42, very few were 

 taken. Between South Georgia and the Falkland Islands in February 1927, large 

 numbers were taken at St. WS 69 across the line of Antarctic Convergence at depths 

 between 250 m. and the surface with smaller numbers extending down to 750 m. (see 

 Fig. 44). At St. WS 70 only a few were taken between 750 and 500 m. A detailed 

 statement of their distribution is tabulated in Appendix II. 



Globigerina conglomerata has not been recorded before in the Antarctic Zone. G. bul- 

 loides is a cosmopolitan species, being most abundant in the tropical seas but extending 

 in small numbers both into the Arctic and Antarctic, where in the higher latitudes its 

 place is taken by G. dutertrei and G. pachyderma (see Heron-Allen and Earland (1922)). 



DXI J 3 



