DINOFLAGELLATA 327 



Genus Heterodinium Kofoid. Flattened or spheroidal; 2 large 

 antapical horns; annulus submedian; with post-cingular ridge; sulcus 

 short, narrow; shell hyaline, reticulate, porulate; salt water. Numer- 

 ous species. 



H. scrippsi K. (Fig. 132, i). 130-155/x long; Pacific and Atlantic 

 (tropical). 



Genus Dolichodinium Kofoid and Adamson. Subcorneal, elongate; 

 without apical or antapical horns; sulcus only 1/2 the length of hy- 

 potheca; plate porulate; salt water. 



D. lineatum (Kofoid and Michener) (Fig. 133, a). 58/z long; eastern 

 tropical Pacific. 



Genus Goniodoma Stein. Polyhedral with a deep annulus; epi- 

 theca and hypotheca slightly unequal in size, composed of regularly 

 arranged armored plates; chromatophores small brown platelets; 

 fresh or salt water. 



G. acuminata (Ehrenberg) (Fig. 133, b). About 50> long; salt water. 



Genus Gonyaulax Diesing. Spherical, polyhedral, fusiform, 

 elongated with stout apical and antapical prolongations, or dorso- 

 ventrally flattened; apex never sharply attenuated; annulus equa- 

 torial; sulcus from apex to antapex, broadened posteriorly; plates 

 1-6 apical, 0-3 anterior intercalaries, 6 precingulars, 6 annular 

 plates, 6 postincingulars, 1 posterior intercalary and 1 antapical; 

 porulate; chromatophores yellow to dark brown, often dense; with- 

 out stigma; fresh, brackish or salt water. Numerous species (Kofoid, 

 1911; Whedon and Kofoid, 1936). 



G. polyedra Stein (Fig. 133, c). Angular, polyhedral; ridges along 

 sutures, annulus displaced 1-2 annulus widths, regularly pitted; salt 

 water. "Very abundant in the San Diego region in the summer 

 plankton, July-September, when it causes local outbreaks of 'red 

 water,' which extend along the coast of southern and lower Cali- 

 fornia" (Kofoid, 1911; Allen, 1946). The organisms occurred also in 

 abundance (85 per cent of plankton) in pools of sea water off the 

 beach of Areia Branca, Portugal, and caused "red water" during the 

 day and an extreme luminescence when agitated at night (Santos- 

 Pinto, 1949). 



G. apiculata (Penard) (Fig. 133, d). Ovate, chromatophores yel- 

 lowish brown; 30-60/x long; fresh water. 



Genus Spiraulax Kofoid. Biconical; apices pointed; sulcus not 

 reaching apex; no ventral pore; surface heavily pitted; salt 

 water. 



S. jolliffei (Murray and Whitting) (Fig. 133, e). 132^ by 92^; 

 California (Kofoid, 1911a). 



