The Mastigophora 147 



Fig. 4. 23. A. Ceratium hirundinella O. F. M., ventral view; diagram- 

 matic (after Entz). B-D. Dinophysis diegensis Kofoid, ventral, dorsal, and 

 right lateral views; B, C, x445; D, x505 (after K.). E, F. Dolichodinmm 

 lineatum (Kofoid and Michener) Kofoid and Adamson, dorsal and ventral 

 views; x700 (after K. & A.). Key: g, gullet; s, sulcal area. 



lacking, as in some strains of C. furcoides (Levander) Langhans; in addi- 

 tion, the antapical and postequatorial horns may be reduced in length, 

 as in C. brachyceros Daday. The apical horn shows differences in length 

 and is curved instead of straight in C. cornutiim Schrank and C. ciir- 

 virostre Kaas. 



Family 5. Dinophysidae. The elongated body is laterally compressed, 

 with a minute epitheca, and the girdle is bordered by prominent flanges 

 ("collars"). The theca consists of right and left valves, joined in a median 

 suture. Known species are marine. Dinophysis Ehrenberg (252; Fig. 4. 23, 

 B-D), Phalacronia Schiller (252) and Oxyphysis Kofoid are included in 

 the family. 



Family 6. Heterodiniidae. The precingular ledge (or list) is well de- 

 veloped but the postcingular ledge is reduced or absent. A ventral pore 

 lies between the apical pore and the single flagellar pore. The plate 

 formula is 3-4'0-la6"6 6-7' "3"". The family includes Heterodinium 

 Kofoid (Fig. 4. 21, K, L) and Dolichodinium Kofoid and Adamson (Fig. 

 4. 23, E, F). 



Suborder 4. Dinocapsina. A dominant palmella and a gymnodinioid 



