SPIROTRICHA, OLIGOTRICHIA 823 



Family 5 Cycloposthiidae Poche 



Pellicle firm and body rigid; zones of membranellae at anterior 

 and posterior ends; more or less compressed; cytopharynx short 

 and wide; macronucleus elongate; a single micronucleus; 2 or more 

 contractile vacuoles; in horse and anthropoid apes. 



Genus Cycloposthium Bundle. Large, elongate barrel-shaped; 

 cytostome in center of a retractile conical elevation at anterior end; 

 adoral zone conspicuous; an open ring-zone of membranellae near 

 posterior end on both dorsal and ventral sides; pellicle ridged; skele- 



Fig. 351. a, Ophisthotrichum janus, X370 (Dogiel); b, Cunhaia curvata, 

 X670 (Hasselmann); c, Cycloposthium bipalmatum, X300 (Bundle); 

 d, C. dentiferum, X270 (Hsiung), e, Spirodinium equi, X350 (Davis); 

 f, Triadinium caudatum, X300 (Hsiung) ; g, T. minimum, X440 (Hsiung); 

 h, Tetratoxum unifasciculatum, X280 (Hsiung). 



