DINOFLAGELLIDA 105 



chromatophores Mainly holophytic, some holozoic Coastal 

 or fresh water. Numerous species. 



Amphidinium scissum Kofoid and Swezy (Fig. 35, i). 

 Length 50 to 60 microns. In sandy shore. 



Family 6 Blastodiniidae Kofoid and Swezy 



All parasitic in or on plants and animals. Numerous genera. 



Genus Blastodinium Chatton. Parasitic in the alimentary 

 canal of Copepoda. Spindle-shaped, binucleated. The envelope 

 which is not of cellulose nature often with two spirally arranged 

 bristles. Spiral furrows. Chromatophores are often in yellowish 

 brown network. 



Blastodinium spinulosum Chatton (Fig. 35, j). In copepods 

 of the genera Paracalanus and Clausocalanus. 



Genus Chytriodinium Chatton. Parasitic in eggs of plankton 

 copepods. Young individuals grow at the expense of host's egg 

 and when fully formed, the body divides into numerous parts, 

 each producing four swarmers. 



Chytriodinium parasiticum (Dogiel) (Fig. 35, k). In copepod 



egg- 

 Genus Oodinium Chatton. Ovoid or spherical body with a 



short stalk. Ectoparasitic on Salpa, Annelida, Siphonophora, 



etc. 



Genus Apodinium Chatton. With a much longer filiform 



stalk and with two nuclei (Fig. 35, /). Ectoparasitic. 



Genus Haplozoon Dogiel. Parasitic in the intestine of poly- 



chaetes. Haplozoon clymenellae (Calkins) in Clymenella torquata. 



Family 7 Polykrikidae Kofoid and Swezy 



Two, four, or eight individuals permanently jointed. Each 

 individual has a structure similar to Gymnodinium, the sulcus 

 however extending the entire length. Color greenish to pink. 

 Nuclei about one-half the number of individuals. Holozoic. 



Genus Polykrikos Biitschli. With the above-mentioned 

 characters 



Polykrikos kofoidi (Chatton) (Fig. 35, m). Body greenish 

 grey to rose in color. Composed of two, four, eight, or sixteen 

 individuals. The cytoplasm contains nematocysts. Each nema- 

 tocyst possesses presumably a hollow thread, and is discharged 



