584 



This North Atlantic form (f. atlantica n. f.j of which I have 

 given fignres, differs in some respects a little from the Baltic form 



(f. subsalsa n. f., var. baltica Schiitt ex parte), 

 e. g. as regards the direction and cnrva- 

 tnre of the antapical- horns. As shown 

 in the fignres, the antapical horns of f. 

 subsalsa form a blnnt angle at their basal 

 part and are then straight or nearly so, 

 while the horns of f. atlantica are longer, 

 andevenly and faintly,bnt distinctly cnrved. 

 This character seems to be constant at 

 least as regards the two forms in ques- 

 tion, viz. the North Atlantic form and the 

 Baltic and Kattegat form, which two must 

 then be considered as geographical races. 



Fig. 134. Ceratiwn iripos (O. F. Mull. 

 Nitzsch., f. subsalsa n. f., a specimen 

 from the Western Baltic 



81. C. neglectum n. sp. 



In some samples I fonnd a Ceratium which comes near to 

 C. tripos, but is always distinct from it. It is rather robust and 

 has very prominent and broad lists 

 on the horns, especially on the apical- 

 horn. I have also observed it in other 

 samples from the North Atlantic Ocean. 

 From the Færoes it was common in a 

 sample of June 1900, where C. tripos 

 was very rare; it also occurred in a 

 sample of March 1902. Still further 

 investigations will clear the relation 

 between the two species. 



Note. C. bucephalum Cl. was not met 

 with in the samples. 



Sectio Macroccras. Antapical-horns 

 open at the distal end; lists ofthe horns 

 with more or lcss developed spincs. 



82. C. horridum (Cl.) Gran emend., 

 Das Plankton d. Norweg. Nordineeres, 1902, p. 194; C. tripos, var. 

 horrida Cleve, Fish. Board for Scotland, 1897, p. 302, lig. 4: C. tripos 

 var. scotica Schi'itt, Pflanzen leben, p. 70, fig. 35 IV; Ostenfeld, Iagt- 

 tagelser, etc 3 L899 3 p. 57; ibidem, 1900, p. 55; C. tripos \.macroceros i 

 f. intermedia Jørgensen, 1. c. p. 42, PI. I, lig. 10. 



Fig. 135. Ceratium neglectum Ostf., n. sp., 

 two specimens ( l; " i). 



