220 DISCOVERY REPORTS 



Fraser (1936, pp. 137-143) has examined and discussed the larval and adolescent forms 

 taken at these successive visits to the ice-edge in winter, and writes of them: " In April 

 Calyptopis 3 and early Furcilia stages are most abundant, in May Calyptopis stages have 

 disappeared and Furcilia 2 predominates, in June it is Furcilia 6 (the last Furcilia), and 

 in September adolescent forms, which have the chief place." 



Apart from the stations approaching Enderby Land it was at only one place far away 

 from the ice-edge that E. superba was found: to the south-east of Kerguelen (Sts. 861-2). 

 One adult and large numbers of larvae were taken there in late April. Our hydrological 

 observations showed that at both of these stations there was colder Antarctic water de- 

 flected from the south by the submarine ridge that connects Gaussberg on the mainland 

 with Kerguelen. Other typical ice-frequenting planktonic animals were found at these 

 two stations, and not at the stations before and after them. 



E. superba is sometimes found in small numbers to the north of the convergence east 

 of the Falklands ; a strong tongue of Weddell Sea water flows north to this region. 



Fraser (1936, pp. 109-165) has discussed the distribution of is. superba of different ages, 

 in terms of depth, latitude and nearness to ice, taking the records given above into 

 account. In material collected at other times he has found the Metanauplius almost as 

 far north as the convergence in the Falkland Sector and therefore considers that the 

 adults spawn away from the ice. He shows that the Metanauplius to early Furcilia 

 stages have a deep habit, spending most of their time in the southward-flowing warm 

 deep current (see p. 201 of this paper), and he finds in this a reason for the concentration 

 of young and adolescent E. superba near the ice-edge. " The habitat of the late Furcilia 

 and early adolescents is at the surface and predominantly at the ice-edge. They will 

 spread northwards in the northerly flowing surface water (see p. 201 of this paper) with 

 the breaking up and drifting away of the field ice in the spring and summer" (p. 165). 

 As they are carried northwards they will grow and become adult ; they will spawn and 

 the deep-living younger larval stages will be carried south. So it is supposed that, 

 during its life-history, E. superba makes a vertical cycle, along an axis that is approxi- 

 mately longitudinal, in the Antarctic Zone. 



Euphausia crystallorophias. Holt and Tattersall (Figs. 17 and 30 e) 



E. crystallorophias. Holt and Tattersall, 1906, p. 3 ; Tattersall, 190S, pp. 9-12, pi. ii, figs, i-io, 

 pi. iv, fig. 10; Hansen, 1908, p. 6, pi. i, figs. 3 a-c; Zimmer, 1914, p. 426, pi. xxvi, figs. 60-4; 

 Tattersall, 1918, p. 6; 1924, p. 19; Mackintosh, 1934, p. -jbetseqq. ; Hardy and Gunther, 1935, 

 p. 218. 



Not E. crystallorophias, Illig, 1930, p. 500, fig. 182. 



? Euphausia sp. (calyptopis larvae), Rustad, 1934, p. 25. 



Description. The carapace has a right-angled expansion or projection behind the 

 upper part of each eye (Fig. 17 a). The margins between these projections and the 

 rostrum are concave; the rostrum is long and sharp and reaches as far forward as the 

 front of the eyes. The carapace has a gastro-hepatic groove from which a nearly hori- 

 zontal keel runs forward mid-dorsally to and along the rostrum. 



