kofoid: new species of dinoflagellates. 171 



any, shoulders broadly rounded, the major curvature within about one trans- 

 diameter from the sides of the midbody at the level of the girdle. Antapicals 

 often flexed outwardly distally. Their antapices swollen to 0.2-0.5 transdiam- 

 eters in width or partially bifurcate in two subequal lobes, crowded with chro- 

 matophores and amyloid bodies. Thecal surface rugose, shoulders spinulate, a 

 hyaline fin usually present on the postmargin. 



Length, 210-350 /x; distance between arms at girdle, 80-120 /* ; transdiam- 

 eter of midbody, 35-40 /a; length of antapicals, 115-260 /x. 



Stations, 4594-4713. 



Ceratium ehrenbergi, sp. nov. 



Plate 2, Fig. 16. 



A small species of the G. lineatum group with rotund midbody and short 

 horns. Midbody with convex margins and very convex dorsal face, excavated 

 ventrally. Girdle somewhat anteriorly placed, with prominent lists. Apical 

 horn short. Antapicals short, pointed, slightly divergent. Surface with linear 

 striae. 



Length, 90-1 10 /a; transdiameter, 50 p. 



Stations, 4711, 4719. 



Ceratium pacificum, Schroeder. 



Plate 3, Fig. 31. 



A very elongated linear species of the G.furca group without expansion of a 

 midbody. Total length, 20-30 transdiameters at the girdle. Epitheca with 

 straight margins tapering evenly from girdle to apical pore. Hypotheca long, 

 nearly two transdiameters in axial altitude. Left horn linear, in length from 

 girdle to apex about 0.3 of the total length. Right horn parallel to left, straight, 

 tapering, scarcely four transdiameters from girdle to its antapex. Postmargin 

 narrow, girdle narrow and with feeble lists, ventral plate elongated, narrow. 

 Chromatophores irregular, dark yellowish brown in color. Varies greatly in 

 length. 



Length, 400-775 /x; transdiameter, 27-30 ft. 



In Humboldt Current. 



Ceratium dilatata (Karsten). 



Plate 4, Fig. 35. 



A small species resembling C. platycome, but of smaller size, more arcuate 

 postmargin, and more uniformly expanded blade-like antapicals. 



The midbody is about the same size as in G. platycorne, and passes abruptly 

 into the apical horn, rarely tapering into it as it frequently does in that species. 

 The distinguishing features of the species are the antapicals, which continue 

 from the symmetrically arcuate postmargin to the level of the base of the apical 

 or beyond it, in a regular curve, to a position parallel to the apical or even in- 

 curved as in my figure. The ends of the antapicals are not continued in the 



