DINOFLAGELLIDA 101 



The annulus possesses elevated rims. Marine. Several genera. 



Genus Dinophysis Ehrenberg. Body compressed. Chroma- 

 tophores yellow. Marine. 



Dinophysis acuta Ehrenberg (Fig. 34, h). Length about 45 

 microns. Widely distributed. 



Genus Amphisolenia Stein. Epitheca is very small and com- 

 posed of two plates; the large hypotheca, composed also of two 

 elongated plates. Chromatophore unknown. In warm sea 

 water. 



Amphisolenia clavipes Kofoid. 



Genus Oxyphysis Kofoid. Epitheca well developed; sulcus 

 short; sulcal lists feebly developed. Annulus impressed. 

 Pelagic in the sea. 



Oxyphysis oxytoxoides Kofoid (Fig. 34, i). 



Family 3 Phytodiniidae Klebs 



Without grooves or flagella. Chromatophores yellow-brown. 

 A very ill-defined group containing no definite characters of 

 the order. Several genera in fresh or salt water. 



Genus Phytodinium Klebs. Body spherical or ellipsoidal; 

 chromatophores discoidal. 



Phytodinium simplex Klebs (Fig. 34,7). Iri fresh water. 



Genus Stylodinium Klebs. Body ovoidal with a stalk. 



Stylodinitim globosum Klebs (Fig. 34, k). About 40 microns 

 long. Fresh water. 



Tribe 2 Gymnodinioidae Poche 



Naked or covered by a single piece cellulose membrane with 

 the longitudinal and transverse furrows, and two flagella. 

 Chromatophores which are mostly abundantly present are 

 yellow or greenish platelets or bands. Stigma is sometimes pres- 

 ent. Asexual reproduction in the active phase is binary fission, 

 while that in the encysted condition is either binary or multiple 

 division. Nutrition is holophytic, holozoic, saprozoic, or para- 

 sitic. The majority are deep-sea forms; a few coastal or fresh 

 water forms also occur. 



This tribe is divided into the following families: 



With a cellulose membrane Family 1 Glenodiniidae 



Without shell 



