COPEPODA rfg 



abundant between ioo and 50 m. depths, but a few specimens have been recorded 

 between depths of 2000 and 1000 m. Its vertical distribution on the oceanic lines is 

 shown in Fig. 86. Its mean vertical distribution at deep-water stations is shown in 

 Fig. 56. It showed no evidence of a diurnal vertical migration, see Figs, no and 113. 



In seasonal distribution it was more abundant in the late summer and autumn than 

 in spring and early summer; this is further discussed in relation to other forms on p. 266. 



O.frigida was first described by Giesbrecht (1902) from the Belgica collections. It was 

 taken at seven stations in the pack ice by the Gauss 1 Expedition. Brady (1918), in his 

 report of the Aurora collections, writes that "most of the gatherings contained species 

 belonging to the genus Oithona, but I am unable certainly to identify them except in 

 three cases. Most of the species may, I think, be referred to O.frigida". Farran (1929), 

 in his report of the Terra Nova collections, writes that O.frigida was "only found within 

 the Antarctic Circle and most numerous in hauls beneath the ice". On the other hand, 

 he finds that O. similis was common over the whole area traversed from New Zealand to 

 the ice barrier. It is curious that in our area the place of O. similis appears to be taken 

 by O. frigida. Mr Scott only recorded O. similis at one station, and that outside the 

 Antarctic Zone, see below. 



Oithona similis, Claus. Only recorded at one station in deep water towards the 

 Falkland Islands, i.e. north of the Antarctic Convergence. 

 St. WS 69 ... 124 at 1000-750 m. 



It is remarkable that we have no records south of the line of Antarctic Convergence 

 since it was taken in the Antarctic by the 'Belgica', 2 'Gauss' 1 and 'Terra Nova', 3 the 

 last expedition taking it as far south as 78 S. See note above under O.frigida. 



Oithona sp. 



Harpacticidae 

 Microsetella norvegica (Boeck). 

 St. 136 20 at 50-0 m. St. WS 45 ... 16 at 170-0 m. 



It was taken in the Antarctic by the 'Terra Nova' 3 and the 'Aurora'. 4 



1 Wolfenden (1911). 2 Giesbrecht (1902). 3 Farran (1929). 4 Brady (1918). 



25 



