87 (86) Posteroventral stylus or secretory organelle of attachment pres- 

 ent. Usually 2 cytopharyngeal rods. Family DYSTERIIDAE. 



87 (86) No such stylus present. Cytopharyngeal rods in conical group. Family 

 CHLAMYDODONTIDAE. 



88 (86) Zone of membranelles present. 



89 



88 (86) Zone of membranelles absent 91 



89 (88) Cell firm, grooved, buccal cavity midventral, with 3 membranelles. Family 

 CINETOCHILIDAE. 



89 (88) Cell soft, flexible, buccal cavity otherwise. 



90 



33 



