PELAGIC PLANT LIFE 



329 



phorescent of the algae ; biologically they are of the "bladder- 

 type." Other species are elongated (see Fig. 238), straight, 

 or crescent-shaped. Within their cells they form big zoo- 



^r^f -rr T^ 



Fig. 234. 

 a, Ornithocercus splendidus [-\-) ; b, Ornithocercus steinii (^-f^). (G. Murray and Whitting. ) 



Spores, built up exactly like the peridinese type with a ring- 

 furrow and two cilia, for which reason the species of Pyrocystis 

 are included among the peridinese, though their fully-developed 

 cells are really of a quite different type. 



