173 DISCOVERY REPORTS 



Genus Peridinium, Ehrenberg 



Peridinium tripos, Murr. and Whitt. 

 Paulsen, 1908, p. 63, fig. 82. 

 Observed at one sub-tropical station, and at the northernmost station on the home- 

 ward voyage when sub-tropical conditions were again being approached. 



Peridinium antarcticum, Schimper. • 

 Karsten, 1905, p. 131, pi. xix, fig. i. 

 The only common member of the genus within the Antarctic Zone. Abundant round 

 South Georgia during the abnormally warm 1929-30 season, and frequent just to the 

 south of the Antarctic convergence in the Scotia Sea. Rare farther south. 



Peridinium elegans, Karst. 



Karsten, 1905, p. 132, pi. xix, fig. 5. 

 Present in very small numbers to the north of the Weddell Sea area early and late 

 in the season. 



Peridinium turbinatum, Mangin. 

 Mangin, 1922, p. 78, fig. 20. 

 At one station east of the South Sandwich Islands. 



Peridinium oceanicum, Vanh. 

 Lebour, 1925, p. 120, fig. 26 b. 

 Observed at one tropical station in long. 30° W. 



Peridinium globulus. Stein. 

 Lebour, 1925, p. 129, fig. 40. 

 At one tropical station. 



Peridinium spp. 



Minute species belonging to this genus were present at a number of stations in the 

 Antarctic Zone in very small numbers. 



Genus Pyrophacus, Stein 



Pyrophacus horologicum. Stein. 



Lebour, 1925, p. 139, pi. xxix, figs. 4 a-c. 

 Observed at three stations in the tropics on the homeward voyage. 



Genus Ceratium, Schrank 



Ceratium candelabrum (Ehrb.), Stein. 

 Lebour, 1925, p. 143, pi. xxx, fig. 2. 

 At one tropical station in long. 30° W. 



