14 P. T. CLEVE, NOTES ON SOME ATLANTIC PLANKTON-ORGANISMS. 



Ceratium contortum Gourret. 

 Plate VII. Fig 10. 



This species, akin to C. tripos, is too constant for being considered as a merc variety. 

 It has been described by Gourret in Annales du Mus. d'Hist. Nat. de Marseille; zool. vol. 1 

 n:o 8, 1883, Pl. II, tig. 33. Schutt has figured it in Pflanzenleben d. Hochsee, pag. 268, 

 VII b., but not named it. It occurs in the Mediterranean, Indian and Pacific. In the 

 Atlantic it is rather common in the tropical parts, E. of S. America and W. of Africa. 

 If a line be traced on the northern hemisphere from the Cape Verde to the Newfoundland 

 Banks the space on the left of this line represents the area of distribution of this species. 



Ceratium curvicorne v. Daday. 

 Plate VII. Fig. 2. 



This constant and characteristic form described by v. Daday (Termezetrajri ftizetek 

 a mus. Hung. Budapestense vulgata 1887 — 88, Pl. III, fig. 4, 8, 12, 14) as a variety of 

 Cer. tripos, has been figured (without name) in Schutt Pflanzenleben der Hochsee, pag. 

 268, VII a. 



I have met with this species in samples from the Red Sea, the Indian ocean and 

 the tropical Atlantic, where it occurs rather common in ths Equatorial currents, the 

 Brazil current, the Florida current towards the Newfoundland Banks as well as east 

 thereof between 40° — 45° N., in the Sargasso Sea, at the Azores and the Canaries. 



Ceratium flagelliferum Cl. 



Plate VII. Fig 12. 



I have proposed this name in 1899 (Kongl. Sv. Vetensk.-Akad. Handl., Vol. XXXII, 

 n:o 3, pag. 1, nomen nudum) for a characteristic form of the tropical Atlantic. It has 

 been figured by Schutt (Pflanzenleben der Hochsee, pag. 267, fig. 77, V. b, without 

 name) as a form of Ceratium tripos. It may possibly be the same as C. tripos var. in- 

 jlexum Gourret, but I dåre not identify them. This species is remarkable for the small 

 size of the body and the very long horns, the posterior of wich have a characteristic 

 flexure. This species is very common in desm o-plankton of the whole tropical Atlantic, 

 from 29° S. to 45° N. 



Ceratium(?) hyperboreum. N. Sp. 



Plate VIII. Fig. 14. 



By the above name I denote a very small, but characteristic dinotlagellate, of 

 which I have not been able to distinguish the tabulation and which possibly may belong 

 to Peridinium. The longitudinal axis measures 0,07 and the transverse 0,or> millim. The 

 membrane has a coarse and irregular areolation. 



