292 



progress posteriorly and are less evidently spiral in form. In preserved 

 material they are often nearly straight, or more or less curved, with 

 smooth edges. 



The four or eight transverse flagella are equal in length and reach 

 approximately to the mid-dorsal line when in action. The longitudinal 

 flagella are not equal, the hindmost being somewhat longer than any one 

 of the other three or seven, which are about equal to each other in length. 

 In action the hindmost flagellum projects posteriorly parallel to the long 

 axis of the body and functions as a propelling-steering organ. The other 

 three flagella are not confined to their respective furrows but project out 



from the body at a slight angle. They 

 are visible only in certain positions 



tr.f.p 



-tf.fl. 



of the organisms and are seen best 



. const. 



Polykrikos scliioartxi Bütsch. 

 view, showing surface markings, flagella, 

 and flagellar pores in a somewhat con- 

 tracted individual. From life. X. 300. 

 Const., interzooidal constriction; /. /'., 

 longitudinal flagellum; I. f. p., pore of 

 longitudinal furrow; n., nuclei; tr. ft., 

 transverse flagellum; tr. f. p., pore of 

 transverse flagellum. 



in side view as the animal rotates. 

 The most favorable conditions of 

 illumination are necessary to demon- 

 strate their presence. I was not al- 

 ways able to find them, largely, it 

 seems, because the organism is excee- 

 dingly sensitive and speedily suc- 

 cumbs to the electro-chemical stimuli 

 resulting from the use of a water 

 immersion lens, or to the effects of 

 the brilliant illumination necessary 

 for microscopic examination. Persi- 

 stant search demonstrated their pre- 

 sence so frequently that I believe 

 they are normal structures generally 

 present. 



If this be the case, Polykrikos is 

 Ventral unquestionbly a Dinoflagellate, and 

 moreover, not a peculiar organism 

 demanding a separate order for its 

 recej^tion. It is rather one of the 

 Gymnodinidae, as Bergh sug- 

 gested, worthy of generic distinction 



i.l.p. 



because of the peculiar nettling or- 

 gans which it possesses but hardly requiring further isolation unless the 

 Gymnodinidae should be broken up into subfamilies. 



The phenomenon of colonial organization is seen elsewhere in the 

 Dì no flagellata in the more or less temporary association of daughter indi- 

 viduals in chains following rapid fission, as in Ce?'atiwii^ and rarely in 



