4 DISCOVERY REPORTS 



tribute to the production of a complex the hke of which is encountered in no other region 

 of the Antarctic. 



Apart from the stations in the area of the Dependencies of the Falkland Islands, much 

 valuable material was obtained from a series of ice-edge stations extending from east- 

 wards of Bouvet Island to South Georgia: also from stations in the Bellingshausen Sea 

 and from stations made during the first circumpolar cruise of the R.R.S. ' Discovery II ' 

 in 193 1. Respecting the last series of stations I am indebted to Mr D. Dilwyn John, who 

 was senior scientific officer on the ship at that time, for examining the plankton samples 

 and sending me the young euphausians. I have also drawn very greatly on the informa- 

 tion contained in his reports to the Discovery Committee relating to this circumpolar 



cruise. 



A list of the samples in which eggs or young E. superba were obtained is given in 

 Table I. The 70-cm. nets yielded the main supply of younger developmental stages, 

 the i-m. oblique and horizontal nets older larvae and adolescents. The i-m. oblique 

 and horizontal hauls of the circumpolar cruise were at stations most of which were made 

 during the southern winter. Both in time distribution and in the development of the 

 E. superba recorded, the results of the circumpolar cruise form a convenient link between 

 the main body of 70-cm. net results and those of the i-m. nets. 



The plankton samples of the circumpolar cruise were examined by John and only the 

 picked out krill was deah with by the writer. John's search for E. superba covered all 

 stations made between the Antarctic convergence and the ice-edge. 



The positions of all stations from which samples were examined are marked on the 

 maps showing distribution, and indication is provided of the presence or absence of 

 krill. 



METHODS 



A full description of the plankton nets used in obtaining the samples is given in Vol. I 

 of the Discovery Reports (Kemp, Hardy and Mackintosh, 1929) and it is therefore un- 

 necessary to recapitulate it here. The whole catch was examined in the small samples 

 and a portion of the whole was used when very large amounts of plankton were taken. 

 In the search for eggs, Nauplii and Metanauplii the macroplankton was picked out and 

 the residue inspected under a binocular microscope. The Calyptopis and Furcilia stages 

 are sufficiently distinctive to enable them to be identified by eye alone. Drawings of 

 appendages were made from unstained material with the aid of a camera lucida. 



For the measurement of the larvae two scales were used of which the smaller, having 

 62 divisions to i mm., was employed for eggs and small larvae and the larger, having 

 24 divisions to i mm., for more advanced stages of development. In analyses where 

 actual length in millimetres is not important, results have been classified primarily 

 according to the original units of measurement. The corresponding dimensions in 

 millimetres have been added. 



In order to measure the larvae as speedily as possible a shallow trough, having the 

 two long sides at an acute angle, was constructed by cementing strips of glass on a 



