12 (11) Cilia in longitudinal rows. Free-living 13 



12 (11) Ciliary rows spiraled. Cytostome radially compartmented, rosette- 

 shaped. Commensal in or on various invertebrates, especially ar- 

 thropods. Family FOETTINGERIIDAE. 



13 (12) Cytostome at base of proboscis. Three bipolar aboral closely set rows of short 

 cilia. Family TRACHELIIDAE. 



13 (12) Proboscis absent. Cytopharyngeal rods conspicuous. Triple dorsal rows 

 of short cilia lacking. Family NASSULIDAE. 



14 (11) Some ciliary rows terminating along edge of left 

 half of vestibulum 



15 



14 (11) Ciliary rows parallel to left edge of vestibulum and 

 not terminating against its edge 



18 



10 



