312 PROTOZOOLOGY 



the sea, and the substance associated with Gymnodinium and other 

 dinoflagellates causes nose and throat irritations in man. Woodcock 

 (1948) observed that similar irritations can be produced by breath- 

 ing air artificially laden with small drops of the red water contain- 

 ing 56X10 6 dinoflagellates per liter. The irritant substance passed 

 through a fine bacterial filter, and was found to be very stable, re- 

 maining active in stored red water for several weeks. Distribution 

 and taxonomy (Kofoid, 1906, 1907, 1909, 1931; Kofoid and Swezy, 

 1921; Prescott, 1928; Eddy, 1930; Playfair, 1919; Wailes, 1934; 

 Thompson, 1947, 1950; Balech, 1944, 1949, 1951; Rampi, 1950; 

 Chatton, 1952); locomotion (Peters, 1929). 



The Dinoflagellata are subdivided into three major groups: 



Bivalve shell without furrows Suborder 1 Prorocentrinea 



Naked or with shell showing furrows. .Suborder 2 Peridiniinea (p. 313) 



Naked; without furrows; no transverse flagellum 



Suborder 3 Cystoflagellata (p. 329) 



Suborder 1 Prorocentrinea Poche 



Test bivalve; without any groove; with yellow chromatophores; 

 2 flagella anterior, one directed anteriorly, the other vibrates in a 

 circle; fresh or salt water. 



Family Prorocentridae Kofoid 



Genus Prorocentrum Ehrenberg. Elongate oval; anterior end 

 bluntly pointed, with a spinous projection at pole; chromatophores 

 small, yellowish brown; salt water. Species (Schiller, 1918, 1928). 



P. micans E. (Fig. 126, a). 36-52/x long; a cause of "red water." 



P. triangulatum Martin. Triangular with rounded posterior end; 

 shell-valves flattened; one valve with a delicate tooth; surface cov- 

 ered with minute pores; margin striated; chromatophores yellow- 

 brown, irregular, broken up in small masses; 17-22^. Martin (1929) 

 found it extremely abundant in brackish water in New Jersey. 



Genus Exuviaella Cienkowski. Subspherical or oval; no anterior 

 projection, except 2 flagella; 2 lateral chromatophores, large, brown, 

 each with a pyrenoid and a starch body; nucleus posterior; salt 

 and fresh water. Several species (Schiller, 1918, 1928). 



E. marina C. (Fig. 126, b, c). 36-50 M long. 



E. apora Schiller. Compressed, oval; striae on margin of valves; 

 chromatophores numerous yellow-brown, irregular in form; 30-32/x 

 by 21-26/x (Schiller); 17-22 M by 14-1 % (Lebour; Martin); common 

 in brackish water, New Jersey. 



E. compressa (Stein). Flattened ellipsoid test; anterior end with a 



