122 AQUATIC PHYCOMYCETES 



Zoospore with the flagellum posteriorly attached (except in Sphaerita), 



the body generally bearing a single prominent globule 



Sporangium never filling the host cell, with a very short discharge 



papilla or devoid of a specialized discharge apparatus; the 



wall simply bursting at maturity; parasitic in Euglenophy- 



ceae or amoebae 



Parasitic in the nuclei of amoebae Nucleophaga, p. 123 



Parasitic in the protoplasm of Euglenophyceae and amoebae 



Sphaerita, p. 125 

 Sporangium either not filling or filling the host cell, with one or 

 more well-defined discharge tubes: parasitic in algae, fungi, 

 or microscopic animals 

 Sporangium more or less ovoid, spherical, or tubular, never 

 completely filling the host cell or losing its individuality 

 Sporangium with one (rarely more) discharge tube 



Sporangia generally scattered; resting spore not lying 



loosely in a container Olpidium, p. 128 



Sporangia formed in dense clusters; resting spore lying 



loosely in a container Pringsheimiella, p. 157 



Sporangium predominantly with numerous discharge tubes 



Pleotrachelus, p. 158 

 Sporangium more or less completely filling the host cell and 

 assuming its shape 

 Sporangium nearly filling the host cell; its walls, however, 

 never completely fusing with those of the host 



Plasmophagus, p. 164 

 Sporangium completely filling the reproductive organ or 

 hypertrophied part of the host; the walls of host and 

 parasite fused, at least laterally Rozella, p. 165 



OLPIDIOMORPHA Scherffel 



Arch. Protistenk., 54: 515. 1926 

 (Fig. 12 J, p. 124) 



Thallus endobiotic, holocarpic, resembling Olpidium: contents re- 

 fractive, with glistening irregular lumps but without fat globules; spo- 

 rangium inoperculate, with a single discharge tube; zoospores formed 

 within the sporangium, emerging upon the dissolution of the tip of 

 the discharge tube, with a single trailing lateral subapically attached 

 flagellum, the body containing an anterior ring of refractive granules; 

 resting spore not observed. 



