320 PROTOZOOLOGY 



yellowish green chromatophores except at posterior end ; stigma dull 

 orange, below girdle; nucleus ellipsoid, posterior to annulus; pellicle 

 delicate; 17-22ju by 8-1 1/z in diameter. Martin (1929) found that it 

 was extremely abundant in parts of Delaware Bay and gave rise to 

 red coloration of the water ("Red water"). 



Genus Gyrodinium Kofoid and Swezy. Annulus 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 (Schiller, 

 1928a). 



Q. biconicum K. and S. (Fig. 129, h). 68 n long; salt water; off Cali- 

 fornia. 



G. hyalinum (Schilling) (Fig. 129, i). About 24^ long; fresh water. 



Genus Cochlodinium Schlitt. Twisted at least 1.5 turns; annulus 

 descending left spiral; pusules; cytoplasm colorless to highly colored; 

 chromatophores rarely present; holozoic; surface smooth or striated; 

 salt water. Numerous species (Schiller, 1928a). 



C. atromaculatum Kofoid and Swezy (Fig. 129, j). 183-185/x by 

 72ju; longitudinal flagellum 45/x long; off California. 



Genus Torodinium Kofoid and Swezy. Elongate; epicone several 

 times longer than hypocone; annulus and hypocone form augur- 

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

 species (Schiller, 1928). 



T. robustum K. and S. (Fig. 129, k). 67-75/z 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 (Thompson, 1950). 



M . nieuportensis C. (Fig. 129, 1). 28-37/x 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 posterior 

 end; annulus oblique, in anterior 1/3 (Conrad, 1926). 



C. cruciatum C. (Fig. 129, m). 40-50ju by 30-40/z; with trichocysts; 

 brackish water. 



Genus Trochodinium Conrad. Somewhat similar to Amphidi- 

 nium; epicone small, button-like; hypocone with 4 longitudinal 

 rounded ridges; stigma; without chromatophores. 



T. prismaticum C. (Fig. 129, n, o). 18-22/x by 9-12;u; epicone 

 5-7 jit in diameter; brackish water (Conrad, 1926). 



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. 



