NOTES ON SPECIES 173 



Ceratium lineatum (Ehrb.), Cleve. 

 Lebour, 1925, p. 145, fig. 45. 



One of the more numerous forms in the sparse phytoplankton of warm seas, observed 

 at two sub-tropical and five tropical stations in long. 30° W. 



Ceratium pentagonum, Gourret. 

 Mangin, 1922, p. 67, fig. 12. 



Intermediates between the southern f. grandis and f. longisetum (or robustum) were 

 common just to the north of the Antarctic convergence, and at some stations in sub- 

 Antarctic water f. longisetum definitely predominated. 



Ceratium pentagonum f. grandis, Mangin. 



Abundant round South Georgia during the abnormally warm summer of 1929-30 

 and frequently encountered in the extreme north of the Antarctic Zone. It was also met 

 with very rarely farther south. 



Ceratium fusus, Ehrb. 



Lebour, 1925, p. 146, pi. xxxi, figs, i, 46 a. 



This species showed a well-marked maximum in sub-Antarctic water, but attenuated 

 forms were also found fairly frequently in tropical and sub-tropical water (see p. 23). 



Ceratium tripos f. truncata, Lohm. 

 Paulsen, 1908, p. 79, fig. 106. 



Observed at two stations in sub-Antarctic water. 



Ceratium bucephalum, Cleve. 

 Lebour, 1925, p. 151, fig. 47 b, c. 

 Present at the three most northerly tropical stations in long. 30° W. 



Ceratium gibberum f. sinistrum, Gourret. 

 Lebour, 1925, p. 153, fig. 49 b. 



Present at the five most northerly stations in long. 30° W, which probably tend to fall 

 in the comparatively rich zone round the Cape Verde Islands (cf. Peters, 1932). 



Ceratium varians, Mangin. 

 Mangin, 1922, p. 70, fig. 14. 



Present at several sub-tropical and tropical stations. 



Ceratium limulus, Gourret. 



Karsten, 1905, p. 133, pi. xix, fig. 11. 

 Observed at three tropical stations. 

 Ceratium spp. 



Small indeterminate members of this genus were recorded at several stations ; those 

 in the sub-Antarctic Zone appeared to be mainly C. fusus which had recently divided. 



