156 DISCOVERY REPORTS 



Genus Asteromphalus, Ehrenberg, 1844 



The species of this genus encountered in our material are most easily distinguished 

 by the number of radii, omitting the obsolete radius; thus A. hepactis is referred to as 

 a "six-rayed" form. 

 Asteromphalus challengerensis, Castr. 

 Castracane, 1886, p. 134, pi. v, fig. 2. 



This handsome eight-rayed form was present in moderate numbers at a few stations 

 off South Georgia in spring. Farther south it was rare, occurring at only two stations in 

 the Weddell and one in the Bellingshausen Sea. It was not observed in Bransfield 

 Strait, but was present in small numbers at several stations in older Antarctic surface 

 water farther north, apparently finding its optimum just to the south of the Antarctic 

 convergence. Maximum in spring. 



Asteromphalus hepactis (Breb.), Ralfs. 



Karsten, 1905, pi. viii, fig. 11 ; Lebour, 1930, p. 52, fig. 28 a. 



An oceanic six-rayed form characteristic of warmer seas. Present at two stations on 

 the 30th meridian in 31° 16J' S and 21° 13' S, in sub-tropical and tropical surface 

 waters respectively. 

 Asteromphalus hookerii, Ehrb. 



Karsten, 1905, pi. viii, fig. 9; Rattray, 1888-89, P- (>5^- 



An oceanic Antarctic species widely distributed in small numbers, absent from Brans- 

 field Strait. 



Asteromphalus parvulus, Karst. 



Karsten, 1905, p. 90, pi. viii, fig. 14. 

 A five-rayed oceanic Antarctic species, which with A. hookerii has a more southerly 

 distribution than other members of the genus. Present in moderate numbers round 

 South Georgia at a few spring stations. Rare farther south in the Weddell Sea, but fairly 

 frequent in the Bellingshausen Sea. 



Asteromphalus regularis, Karst. 



Karsten, 1905, p. 90, pi. viii, fig. 12. 

 This oceanic seven-rayed form was by far the commonest member of the genus in 

 the material from the spring survey round South Georgia and in the northern part of 

 the Weddell Sea area, where it was observed in moderate numbers at many stations. 

 It was only recorded once in the Bellingshausen Sea itself, and was rare in older water 

 of Bellingshausen Sea origin. Like A. challengerensis it appears to find its optimum in 

 the older Antarctic surface water not far south of the convergence in spring, but it has 

 a much wider range to the southward, especially in the Weddell Sea. 



Genus Actinocyclus, Ehrenberg, 1839 



Actinocyclus bifrons, Karst. 



Karsten, 1905, p. 92, pi. ix, fig. 8. 



