DISTRIBUTION OF ANTARCTIC MACROPLANKTON 



i47 



and at Sts. 647-9 there is a very uniform plankton. At all these stations Rhincalanus is 

 the dominant copepod, Limacina is found only near the convergence, the Chaetognatha 

 for the most part increase steadily towards the north, and Parenchaeta and Eiiphamia 

 frigida (except at St. 649) are present in moderate numbers at night stations. Calanus 

 acutus and C. propinquus are a little variable, but Parathemisto has a uniform distribution 

 in each line, except for a large catch at St. 384. Thysanoessa occurs in large numbers on 

 the first line, but in smaller numbers on the other two. In general it may be said that 

 there is a close similarity in the catches at consecutive stations across this part of the 

 northern zone, and if one or two species, such as Thysanoessa, are excepted, it can be 

 said that there was little difference between the plankton taken on the three lines. 



North-east of Drake Passage there are several lines of stations lying roughly between 

 the Falkland Islands and the South Shetlands and South Orkneys (Figs. 10, 12, 14). 

 These stations and the principal species taken at them are shown in Table XVI. 



The samples taken at WS 203 and WS 204 resemble one another only in respect of 

 certain species. Thus the numbers of Chaetognatha, Parathemisto, and Parenchaeta are 

 similar, but Rhincalanus is the dominant copepod only at WS 203, and Thysanoessa 

 occurs only at that station. The suggestion of an increase in the number of Limacina 

 towards the north is in accordance with the conditions found in Drake Passage. The 

 November line (WS 469-74) shows again the uniform plankton indicated in Drake 

 Passage. At each station but one Rhincalanus is, as before, the dominant copepod, Calanus 

 acutus is uniformly distributed in modest numbers and the Chaetognatha steadily in- 

 crease towards the north. Limacina, Thysanoessa, Calanus propinquus, C. simillimus, 

 and Parenchaeta are scarce. WS 527-9 give curious results. The hauls were all taken in 

 the middle of the daytime and consequently are not very reliable, but the plankton is 

 not of the usual type found in the northern zone. The quantity is small, Calanus 



