Chapter 31 

 Order 1 Holotricha Stein (continued) 



Suborder 2 Gymnostomata Blitschli 



Cy tostome at or near anterior end Tribe 1 Prostomata 



Cytostonie not at or near anterior end 



Cytostome lateral, narrow or round 



Tribe 2 Pleurostomata (p. 517) 



Cytostome ventral, in anterior half .Tribe 3 Hypostomata (p. 522) 



Tribe 1 Prostomata Schewiakoff 



Free-living 



Cytostomal region con>pressed; bearing trichites 



Family 1 Spathididiidae 



Cytostomal region not compressed 



Cytostome opens into anterior receptaculum; with lorica 



Family 2 Metacystidae (p. 499) 



Cytostome at tip of apical cone. . . .Family 3 Didiniidae (p. 499) 

 Cytostome otherwise 



Body covered with regularly arranged, perforated, ectoplasmic 



plates Family 4 Colepidae (p. 501) 



Body not covered with plates 



With radially arranged tentacles 



Family 5 Actinobolinidae (p. 503) 



Without tentacles Family 6 Holophryidae (p. 503) 



Parasitic in mammalian gut Family 7 Butschliidae (p. 513) 



Family 1 Spathidiidae Kahl 



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

 pressed; anterior region slightly narrowed into a neck, and trun- 

 cate; cihation uniform; cytostome occupies whole anterior end; 

 contractile vacuole posterior; macronucleus elongate; several 

 micronuclei; trichocysts around cytostome and scattered through- 

 out; fresh or salt water. Numerous species. 



S. spathula (Mliller) (Figs. 21; 229, a, h). Up to 250^ long; fresh 

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

 organism. 



Genus ParaspathidiumNoland. Form resembles that of Spathid- 

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

 strong cilia and on the other by weaker ones and a shelf-hke, non- 

 undulatory membrane; 2 longer cilia on dorsal edge near anterior 



49) 



