DINOFLAGELLATA 225 



Bay and gave rise to red coloration of the water ("Red water"). 



Genus Gyrodinium Kofoid et Swezy. Annuliis descending left 

 spiral; sulcus extending from end to end; nucleus central; pusules; 

 surface smooth or striated; chromatophores rarely present; cyto- 

 plasm colored; holozoic; salt or fresh water. Many species. 



G. hiconicum K. et S. (Fig. 102, h). 68m long; salt water; off Cali- 

 fornia. 



G. hyalinum (Schilling) (Fig. 102, i). About 24^ long; fresh- 

 water. 



Genus Cochlodinium Schiitt. Twisted at least 1.5 turns; annu- 

 lus descending left spiral; pusules; cytoplasm colorless to highly 

 colored; chromatophores rarely present; holozoic; surface smooth 

 or striate; salt water. Numerous species. 



C. atromaculatum Kofoid et Swezy (Fig. 102, j). 183-185m by 

 72m; longitudinal flagellum 45ju long; ofif California. 



Genus Torodinium Kofoid et Swezy. Elongate; epicone several 

 times longer than hypocone; annulus and hypocone form augur- 

 shaped cone; sulcus long; nucleus greatly elongate; salt water. 2 

 species. 



T. robustum K. et S. (Fig. 102, h). Ql-7^ti long; off California. 



Genus Massartia Conrad. Cylindrical; epicone larger (9-10 

 times longer and 3 times wider) than hypocone; no sulcus; with 

 or without yellowish discoid chromatophore. 



M. nieu'portensis C. (Fig. 102, I). 28-37m long; brackish water. 



Genus Chilodinium Conrad. Ellipsoid; posterior end broadly 

 rounded, anterior end narrowed and drawn out into a digitform 

 process closely adhering to body; sulcus, apex to 1/5 from pos- 

 terior end; annulus oblique, in anterior 1/3. 



C. crvciatum C. (Fig. 103, m). 40-50/x by 30-40^; with trich- 

 ocysts; brackish water. 



Genus Trochodinium Conrad. Somewhat similar to Amphidin- 

 ium; epicone small, button-hke; hypocone with 4 longitudinal 

 rounded ridges; stigma; without chromatophores. 



T. prismaticum C. (Fig. 102, n, o). 18-22^ by 9-12^; epicone 

 5-7m in diameter; brackish water. 



Genus Ceratodinium Conrad. Cuneiform; asymmetrical, color- 

 less, more or less flattened; annulus complete, oblique; sulcus on 

 half of epicone and full length of hypocone; stigma. 



C. asymetricum C. (Fig. 102, p). 68-80^ by about 10^; brackish 

 water. 



