RHINCALANUS GIGAS 293 



November (St. 1045), but in March open water was found throughout the whole length 

 of the line in that month from St. 1138 to St. 1153. 



PREVIOUS WORK 



The species Rhincalamis gigas was first described by Brady (1883) from the collections 

 of H.M.S. 'Challenger', and subsequently Giesbrecht (1902) described a species from 

 the collections of the Belgica Expedition which he called R. grandis and which he be- 

 lieved to be identical with the R. gigas of Brady. Wolfenden also found this species in 

 the Gauss collections (Wolfenden, 191 1) and in the Discovery collections (Wolfenden, 

 1908), and established that the species described by Brady and Giesbrecht were the 

 same. R. gigas was also taken by the Terra Nova (Farran, 1929), by the Scotia (Scott, 

 1912) and by the Aurora (Brady, 1918) Expeditions. 



Schmaus and Lehnhofer (1927) gave an account of the young copepodite stages of the 

 species from the Valdivia collections, and it is from the description of these authors that 

 the copepodite stages have been identified during the present work. 



In the Antarctic summer of 1929-30 the floating factory ' Vikingen ' took a number of 

 plankton stations between the South Sandwich Islands and Bouvet Island and between 

 the South Orkney Islands and the South Sandwich Islands. The collections from these 

 stations, together with one station taken by the 'Norvegia' in 1928, form the subject of 

 a paper by Ottestad (1932), in which the author dealt with the biology of certain of the 

 more important species of macroplanktonic Copepoda. In the short section devoted to 

 R. gigas the author arrived at certain conclusions which are to a large extent confirmed in 

 the present report.^ 



Hardy and Gunther (1935) have given some account of the distribution, both hori- 

 zontal and bathymetrical, of the species in the immediate vicinity of South Georgia, and 

 Mackintosh (1934) included the species in his general account of the horizontal distribu- 

 tion of the macroplankton in the Falkland Sector. 



It is not intended in this report to give a description of the species, for which reference 

 should be made to the accounts of Brady (1883), Giesbrecht (1902) and Wolfenden 

 (1908, 1911). On the grounds of priority the name R. gigas will be used, as opposed to 

 Giesbrecht's R. grandis. 



DISTRIBUTION OF RHINCALANUS GIGAS 



The material collected by the 'Discovery II' during her 1931-3 commission is far 

 more comprehensive than that of any previous expedition, although only a portion of it 

 has been examined and forms the subject of this paper. It will scarcely serve any pur- 

 pose, therefore, to give former records of the occurrence of R. gigas, but it may be noted 



1 While the present report was in the press a further important paper by Ottestad has appeared 

 (Ottestad, P., 1936. On Antarctic Copepods from the "Norvegia" Expedition 1930-1. Scientific Results 

 of the Norwegian Antarctic Expeditions 1927-8 et sqq. Norske Vid. Akad., Oslo, No. 15, pp. 1-44, text- 

 figs, i-ii). The paper deals with the biology of four of the commonest Antarctic species, Calanus 

 acutus, C. propinquus, Rhincalanus gigas and Metridia gerlachei. 



