DINOFLAGELLATA 



313 



depression through which two flagella emerge; two chromatophores 

 pale or deep green, each with a pyrenoid; nucleus posterior; no 

 stigma; 22-26/x by 15-18/z by 11-12/*; fresh and salt water (Thomp- 

 son, 1950). 



Suborder 2 Peridiniinea Poche 



Typical dinoflagellates with one to many transverse annuli and 

 a sulcus; 2 flagella, one of which undergoes a typical undulating 

 movement, while the other usually directed posteriorly. According 



Fig. 126. a, Prorocentrum micans, X420 (Schiitt); b, c, Exuviaella 

 marina, X420 (Schiitt); d, e, Cystodinium steini, X370 (Klebs); f, Gleno- 

 dinium cinctum, X590 (Schilling); g, G. pulvisculum, X420 (Schilling); 

 h, G. uliginosum, X590 (Schilling); i, G. edax, X490 (Schilling); j, 

 G. neglectum, X650 (Schilling). 



to Kofoid and Swezy, this suborder is divided into two tribes. 



Body naked or covered by a thin shell Tribe 1 Gymnodinioidae 



Body covered by a thick shell Tribe 2 Peridinioidae (p. 324) 



Tribe 1 Gymnodinioidae Poche 



Naked or covered by a single piece cellulose membrane with an- 

 nulus and sulcus, and 2 flagella; chromatophores abundant, yellow 

 or greenish platelets or bands; stigma sometimes present; asexual 

 reproduction, binary or multiple division; holophytic, ho lo zoic, or 



