A List of the Species of Ceratium in Japan. 



BY 



K. Okamura and T. Nishikawa. 



With Plate VI. 



The following annotated list of Ceratium found in the seas around 

 Japan was drawn up chiefly from the notes and figures taken by T. 

 Nishikawa from among the plankton material collected at several places 

 by instigations of the Imperial Fisheries Bureau of the Japanese govern- 

 ment. 



The task of identification had devolved upon K. Okamura, who 

 also had opportunities of independently collecting and studying some 

 species on the coast of Prov. Bôshyû. 



Owing to our want of access to certain necessary reference papers, 

 we have been compelled to leave undecided the systematic status of some 

 of the forms but to mark them either with query or as provisionally new. 



The references given under each of the forms are only those which 

 could have been consulted by us. 



Ceralium tripos Duj. 

 (Fig, I). 



• Cleve, '02, p. 2S. — '01, p 231. — '97 a, p. 301, fig. r, (typical C. tripos).- — '97 b, 

 p. 25. (C. tripos Nitzsch.). 

 Gourret, '33, p. 23 (C. tripos Nitzsch.). 

 Hensen, '37, Taf. VI, fig. 57. 

 Schritt, '93, p. 2Ê6, fig. IV, a (without name). 

 Schröder, '01, p. 15, Taf. I, fig. 17 a (C. tripos Nitzsch.). 

 Gran, '02, p. 193 (C. tripos [O. F. Müller] Vanh.). 



