ioo DISCOVERY REPORTS 



Orkneys, and the eastern Weddell Sea. It generally occurs in ones and twos, but catches 

 up to ioo were taken in the eastern Weddell area. 



Calanus acutus. Numerically this is the most important species of all. It is dis- 

 tributed throughout the Antarctic surface waters, and there have been catches of iooo 

 or more everywhere from the convergence to the cold waters of the Bellingshausen and 

 Weddell Seas. The very big catches of 5000 and more have been taken only in the South 

 Georgia and South Sandwich areas, the western Bellingshausen and eastern Weddell 

 Seas. The species is on the whole evenly distributed and there is no tendency to form 

 shoals. 



Calanus propinquus. This species also is found everywhere in both the warm and 

 cold parts of the Antarctic surface water, but the largest catches have been taken in the 

 neighbourhood of South Georgia and the South Sandwich Islands. It has no tendency 

 to form shoals, but is perhaps a little more localized than C. acutus. For instance at 

 Sts. 360-74 in February and March, 1929-30, it was taken in enormous numbers in the 

 eastern part of the Scotia Sea, and it was by far the most prominent copepod at 

 Sts. 453-72 between Bouvet Island and South Georgia in October 1930-1. Specimens 

 taken near the Antarctic convergence are mostly immature. 



Calanus simillimus. Normally confined to the warmer waters of the Antarctic. It has 

 not been taken in the Bellingshausen or Weddell Seas and has not often appeared south 

 of a line running from the north side of the South Shetlands to South Georgia, though 

 around South Georgia it is common enough. In March of the warm 1929-30 season, 

 however, it was taken at Sts. 372-5, west of the South Sandwich Islands. This is normally 

 quite an evenly distributed species, and an abnormally large catch has been taken only 

 once, at WS 184, where over 40,000 were taken at a point close to the south coast of South 

 Georgia. The next largest catches were 5000 at WS 466 just on the north side of the 

 convergence, and 2200 at St. 321 off South Georgia. 



Rhmcalanus gigas. This species has been caught in large numbers at practically every 

 station in the warmer parts of the Antarctic, and there is little doubt that it is abundantly 

 and evenly distributed in these waters at least during the greater part of the summer. 

 It is also taken in large numbers in the Bellingshausen Sea and in the Weddell Sea 

 water, but here it is not by any means always found in abundance. It occurs in small 

 numbers, though at most stations, in the coastal regions of the South Orkneys, South 

 Shetlands and eastern Bellingshausen Sea. It shows no tendency to form shoals, and 

 cannot be regarded as any more patchy than any of the other more numerous species. 

 Pleuromamma robusta. This is a warm-water species whose proper habitat in Ant- 

 arctic water appears to be the outer belt immediately south of the convergence. It is 

 of course also found north of the convergence. It is not uncommon in the Weddell Sea 

 water on both the west and east sides of the South Sandwich Islands, but it has occurred 

 at none of the stations in coastal regions of the South Orkneys and South Shetlands, nor 

 in the Bellingshausen or eastern Weddell Sea. As a rule it is as evenly distributed as 

 most of the other copepods, but a very exceptional catch of over 6000 was taken at 

 St. 452, north of Bouvet Island. 



