90 (89) Zone of membranelles bordering anterior end. Length over 70 /jm. 

 Family PERITROMIDAE. 



90 (89) Zone of membranelles reduced, limited to buccal cavity. Length under 70 /xm 

 Protocruzia, order Heterotrichida (see Annotated Systematic List). 



91 (88) Cilia ventral in dense curving band. Motile larval stages in life cycle of 

 members of the order Chonotrichida. 



91 (88) Cilia in C-shaped rows along borders of cell. Askoella, 

 Conidiophrys (tomite only), and Phthorophyra. Family 

 ASKOELLIDAE (also see couplet 112). 



92 (85) Cytostome apical or lateral often inconspicuous 93 



92 (85) Cytostome absent 97 



93 (92) Cytostome anterior 



93 (92) Cytostome a lateral slit. 



94 

 96 



34 



