Chapter 32 

 Order 1 Holotricha Stein (continued) 



Suborder 2 Gymnostomata Biitschli 



Cytostome at or near anterior end Tribe 1 Prostomata 



Cytostome not at or near anterior end 



Cytostome lateral, narrow or round. . .Tribe 2 Pleurostomata (p. 580) 

 Cytostome ventral, in anterior half. . . .Tribe 3 Hypostomata (p. 585) 



Tribe 1 Prostomata Sc;hewiakoff 

 Free-living 



Cytostomal region compressed; bearing trichites 



Family 1 Spathidiidae 



Cytostomal region not compressed 



Cytostome opens into anterior receptaculum; with lorica 



Family 2 Metacystidae (p. 563) 



Cytostome at tip of apical cone Family 3 Didiniidae (p. 563) 



Cytostome otherwise 



Body covered with regularly arranged, perforated, ectoplasmic 



plates Family 4 Colepidae (p. 565) 



Body not covered with plates 



With radially arranged tentacles 



Family 5 Actinobolinidae (p. 566) 



Without tentacles Family 6 Holophryidae (p. 567) 



Parasitic in mammalian gut Family 7 Biitschliidae (p. 576) 



Family 1 Spathidiidae Kahl 



Genus Spathidium Dujardin. Flask- or sack-shaped; compressed; 

 anterior region slightly narrowed into a neck, and truncate; ciliation 

 uniform; cytostome occupies whole anterior end; contractile vacuole 

 posterior; macronucleus elongate; several micronuclei; trichocysts 

 around cytostome and scattered throughout; fresh or salt water. 

 Numerous species. 



S. spathula Miiller (Figs. 21; 267, a, h). Up to 250m long; fresh 

 water. Woodruff and Spencer (1922) made a careful study of the 

 organism. 



Genus Paraspathidium Noland. Form resembles that of Spathid- 

 ium; but cytostome an elongate slit, bordered on one side by strong 

 cilia and on the other by weaker cilia and a shelf-like, nonundulatory 

 membrane; 2 longer cilia on dorsal edge near anterior tip; anterior 

 1/3 compressed; posterior 2/3 nearly cylindrical; 2 oval macro nuclei, 

 each with a micronucleus; cytoplasm filled with numerous refractile 

 granules; about 70 rows of cilia; contractile vacuole terminal; salt 

 water. One species. 



560 



