KOFOIU: NEW SPECIES OF DINOFLAGELLATES. 173 



Ceratium schroeteri, Schroeder. 



Plate 3, Figs. 18, 19. 



A small species resembling G. digitatum, but with less lateral expansion of 

 the epitheca and less curvature of the antapicals than is found in that species. 



Elongated, transdiameter at girdle 0.15 of the total length. Epitheca broad, 

 tapering a short distance from the apex to a short, scarcely delimited apical 

 horn, slightly scoop-shaped and twisted to the left. Antapical horns unequal, 

 the end of the right 1.5 and of the left 2.4 transdiameters from the girdle at the 

 lateral margin. The right horn is straight and tapering ; the left is strongly 

 curved dorsally and to the left, and the wall of its concave face is strongly thick- 

 ened. Thecal wall, of the left antapical especially, scabrous with small spinules 

 at the pores. Chromatophores numerous, irregular. 



Length, 335 n\ transdiameter at girdle, 50 /x. 



Station, 4594. 



Ceratium scapiforme, sp. nov. 



Plate 3, Fig. 23. 



A species of from small to medium size, of the G. furca group showing affinities 

 to both G. pennatum and G. schroeteri. "With long tapering blade-like epitheca 

 not inflated beyond the transdiameter at the girdle, a short oblique scarcely 

 differentiated apical horn, elongated left antapical, and submedian girdle. 



The epitheca is 10-1 1 transdiameters in altitude and its wall is thickened in 

 the region of curvature on the concave face. The apical pore is oblique, open- 

 ing antero-dextrally. The hypotheca is short in altitude, scarcely more than, 

 a transdiameter to the middle of the postobliquity. The right antapical is 

 short and straight, its antapex being about a transdiameter from the girdle. The 

 left antapical is curved dorsally and to the left throughout its length, the curva- 

 ture near its base being somewhat greater than it is distally. The concave 

 faces of both apical and left antapical horns have thickened walls. 



Length, 460-530 fi ; transdiameter, 25 p. 



Stations, 4719, 4740. 



Ceratium tricarinatum, sp. nov. 



Plate 3, Fig. 20. 



A medium-sized species of the G. furca group with affinities to G. bigelowi, 

 C. digitatum, and possibly G. geniculatum. Distinguished by the inflation of 

 the epitheca into a tricarinate expansion which in its greatest transdiameter 

 equals or exceeds that at the girdle. 



One of the carinae is middorsal, and the other two latero- ventral, with 

 sutures of the apical plates at two of the angles. The third suture is mid- 

 ventral. The three faces of the midbody are concave, especially anteriorly. 

 The expansion tapers more or less abruptly into the apical horn and bends 

 somewhat to the left as it passes into the horn, which is straight but directed a 

 little ventrally from the axis. 



