2 7 o DISCOVERY REPORTS 



the Southern Ocean, and at station WS 976 one juvenile specimen was taken in the 1000-750 m. haul. 

 The other species, Eachaetomera zurstrasseni (Illig), although originally recorded from the Indian 

 Ocean west of the Chagos Islands, has only been recorded once in the waters to the west of Cape 

 Town, and is usually only taken in the far south of the Atlantic Ocean. One specimen occurred at 

 station WS 976. 



CUMACEA 



The Cumacea were identified by Dr N. S. Jones and the following account has been abstracted from 

 his report on the group (1955). 



Four genera and five species were present in the samples, but only the genus Iphinoe attained con- 

 siderable numerical importance. This is not altogether surprising, for the Cumacea are normally 

 bottom-living forms, but the appearance of one species (Iphinoe fagei, Jones) in considerable numbers 

 in the plankton— exceeding 7000 in one haul at station WS 989 — is of great interest. 



The collections of Cumacea are confined to the stations relatively close to the coast, in shallow water. 

 Evidently there is a succession of species from north to south. Bodotria glabra Jones occurred only in 

 small numbers and only on the most northerly line of stations (19 44' S). On both the Walvis Bay 

 line and Sylvia Hill line the two species of Iphinoe, I. africana Zimmer and /. fagei, were dominant 

 in abundance. Upselaspis caparti (Fage) was present only off Walvis Bay and Diastylis rufescens Jones 

 occurred only on the Orange river line. 



The large catches of Cumacea occurred in the night hauls at stations WS 988 and 989, and I. fagei 

 was the most abundant species. Jones notes that 'although the species present in these hauls may be 

 able to live normally in the plankton, they show no special adaptations to this mode of life and their 

 nearest relatives are coastal bottom-living forms'. Further, he says that when Cumacea have been 

 caught in tow-nets at night, adult males have usually predominated, especially when attracted by 

 artificial light, although in some recent records newly moulted adult or ovigerous females have out- 

 numbered the males. In the hauls containing the largest numbers of specimens described here, both 

 males and females of all stages were represented. These could possibly have been a nuptial swarm, 

 but the following is a rather attractive alternative explanation. 



It is interesting to compare these catches with a sample of the bottom fauna taken near Walvis Bay 

 by Professor Spark (1953). Here, in the belt of sand inside the anaerobic zone (p. 204), Spark took 

 1910 Cumacea in a Petterson grab sample. Both stations WS 988 and 989 lay over the anaerobic zone, 

 and if Spark's specimens were the same species, Iphinoe fagei, then it seems reasonable to suppose that 

 the great development of the anaerobic zone in March may have forced the Cumaceans up from their 

 usual habitat on the sea-bed, to adopt a planktonic existence in the waters nearer the surface where 

 oxygen would have been available. 



The numbers of Iphinoe sp. corresponded closely with the distribution of the pilchard eggs and 

 larvae (see p. 272). 



Amphipoda 

 Although the amphipods have been separated from the samples, they have not been identified further, 

 and it is only possible to remark on the total abundance of the group. They were present in relatively 

 small numbers at all of the stations except WS 981. Their greatest abundance was at the offshore 

 stations, where at WS 986, over 270, which appear to be mainly juvenile Vibilia sp., occurred in the 

 50-0 m. haul, but they were also present in moderate numbers at the inshore stations on the Orange 

 river line. These Vibilia sp. appeared in numbers at stations where salps were also abundant, as was 

 to be expected from the known commensalism between these animals. 



