io2 DISCOVERY REPORTS 



Parathemisto gaudichaudi. The big catches of this species have all been taken in the 

 warmer parts of the Antarctic water, including the South Georgia whaling grounds. 

 Moderate numbers have occurred in the South Sandwich region and small numbers in 

 the coastal region of the South Orkneys and South Sandwich Islands and in the Bellings- 

 hausen Sea. In the warmer waters there are practically no night stations at which it was 

 not present, but there is no doubt that it is a patchy species and it sometimes occurs 

 in dense local concentrations. During the 1927-31 period 2000-3000 have been taken 

 on several occasions, and some very big hauls were taken off South Georgia during the 

 first commission of the ' Discovery '. Sometimes, however, it is distributed quite evenly 

 over a large area. 



Primno macropa. This species seems to have no particular limits to its distribution 

 in the Antarctic. It is perhaps slightly commoner in the warmer waters, but it is found 

 in small numbers almost everywhere. There is no evidence of any tendency to form 

 shoals or local concentrations. 



Vibilia antarctica. Found everywhere from the convergence to the Bellingshausen 

 and Weddell Seas. It seems to be of very regular occurrence around the South Orkneys. 

 It never occurs in very large quantities. 



Eusirns antarcticus. Another strictly cold-water species whose northern limit corre- 

 sponds closely with that of Diphyes antarctica. Few specimens have been taken and 

 there is no reason to suppose that its distribution is at all patchy. 



Cyllopus spp. Quite evenly distributed from the convergence to the colder regions. 

 As a genus it seems to have no preference for either the warmer or colder parts of the 

 Antarctic, and there appears to be no tendency towards local concentrations. 



Antarctomysis sp. This must be classed as a neritic genus. Among the samples upon 

 which the present paper is based it has been found only in the South Georgia and South 

 Sandwich region, but according to Rustad (1930, Mysidacea, p. 20) its distribution is 

 circumpolar. The greatest number have been taken from the shallow water on the south 

 side of South Georgia. 



Euphausia snperba. In its habits and distribution the " krill ", as it is commonly called, 

 stands apart from all other macroplankton species. It will form the subject of separate 

 publications, and it will suffice here to say that it is seldom found north of a line running 

 from the north side of the South Shetland Islands north-eastwards past the western end 

 of South Georgia, and it has not so far been taken in any large numbers in the Bellings- 

 hausen and eastern Weddell Seas. It is one of the few species which are found in 

 occasionally large numbers in the coastal region of the South Orkneys and South 

 Shetlands. The average number for all hauls (see Table II, p. 97) shows that numeri- 

 cally it is among the most abundant of macroplankton species, and in mass of living 

 matter it might well be equal to all the rest of the Antarctic macroplankton combined. 

 In its distribution it is the most patchy and irregular of these species, and the great 

 majority of specimens have been taken from actual shoals. 



Euphausia frigida. This species occurs mainly in the warm waters of the outer Ant- 

 arctic Zone and in the outflowing Weddell water in the South Sandwich neighbourhood. 



