KOFOID AND MICHENER: DINOFLAGELLATES. 279 



Protoceratium pepo, sp. nov. 



A subellipsoidal species of medium size with coarse mesh. Body sub- 

 ellipsoidal with broadly rounded symmetrical apex and antapex. Length 

 1.3 transdiameters. Epitheca less than hypotheca, its altitude 0.5 trans- 

 diameter, its sides not sufficiently convex to be hemispherical or straight 

 enough for a cone. Apex broadly rounded, apical area small. Hypotheca 

 of similar form to epitheca but longer, its altitude 0.67 transdiameter. Girdle 

 descending, displaced 1 girdle width, its furrow slightly impressed, with very 

 low, hyaline non-ribbed lists. Ventral area very slightly widened to the right, 

 with long hyaline fin on right margin, its length from anterior girdle list 0.65 

 transdiameter and its greatest width 1.45 girdle widths. Surface coarsely 

 reticulate with rounded polygons, longer along faintly marked sutures, three 

 rows and a distal group on each half of the theca. Ventral pore in small 

 precingular 1". Numerous scattered minute pores. 



Length 46 n; transdiameter, 36 n. 



Sta. 4681. 



Protoceratium promissum, sp. nov. 



A large species of elongated form with coarse mesh and light secondary 

 reticulations along tropical sutures. Body elongated almost biconical. 

 Length 1.6 transdiameters, girdle section circular, some ventral flattening. 

 Epitheca less than hypotheca, its altitude 0.75 transdiameter, its sides nearly 

 straight, apex squarely truncate, 1.3 girdle widths across. Hypotheca 0.86 

 transdiameter in altitude, sides sloping, nearly straight proximally, antapex 

 broadly rounded. Girdle descending, displaced 0.4 girdle width, its furrow 

 deeply impressed, with heavy ridges and very low, hyaline, non-ribbed lists. 

 Ventral area spreading distally, angled on right with low fin, its length from 

 anterior girdle list 0.78 transdiameter. Surface coarsely reticulate with 

 somewhat rounded polygons, larger and longer near faintly marked sutures, 

 smaller and more rounded in center of plates. Faint traces of secondary 

 reticulations in places along the two tropical suture lines. Ventral pore in 

 small precingular 1". No pores. 



Length, 70 n; transdiameter, 43 m- 



Sta. 4739. 



Peridiniella, gen. nov. 



Theca consisting of an apical series of plates (4), an incomplete zone of 

 dorsal intercalaries (3), seven precingulars, six girdle plates, six postcingulars, 

 one posterior intercalary, and one antapical. Resembles Peridinium in the 

 dorsal intercalaries, and in number of precingular plates. Resembles Gonyau- 



