UNEVENNESS OF OCEANIC PLANKTON 523 



whether the gap in the phytoplankton is due to the grazing action of the large number of 

 euphausians. The concentration of euphausians cannot be only an apparent one due to 

 a possible reduced filtration on the other parts of the roll caused by the phytoplankton ; 

 if this were so the concentration would begin as soon as the phytoplankton becomes re- 

 duced. A small isolated patch of Limacina is also a feature of the record. The Copepoda 

 were never abundant. Hyperiid amphipods were taken in isolated ones and twos along 

 the roll. 



I00-| 



EUPHAU5IACEA juv. 

 COPEPODA 



80 



60 



40- 



20 



▲ 

 HOUR.o 



Fig. 10. Variations in the numbers of the predominant plankton organisms, Copepoda continuous line and 

 Euphausiacea juv. broken line, on Record 13 taken between four stations off the north-east coast of South 

 Georgia along a total distance of 30-6 miles. 



Record 13 



Date: 3. iii. 26. 



Times: 1400-0000 (see Fig. 10). 



Position: 15-4 to 46 miles N 46° E of Jason Light, South Georgia. 



Distance: 30-6 miles. 



This record is taken under coastal rather than oceanic conditions, being run between 

 four stations off the north-east coast of South Georgia. It shows well (Fig. 10) the 

 patchy nature of the distribution of young euphausians. The Copepoda show a general 

 increase with the approach of night. 



