28 (27) No anterior suctorial tentacle present. Macronucleus 

 long, axial. Endocommensal in gut of worms, particu- 

 larly polychaetes. Family ANOPLOPHRYIDAE. 



29 (2) A zone of 6 or more (commonly 25 

 to more than 100) membranelles 

 anterior to and to the the left of the 

 cytostome 



30 



29 (2) Never more than 4 membranelles present. 



36 



30 (29) Locomotory cilia organized in helical rows of cirri. Family SPIROFILIDAE 

 (also see couplet 99). 



30 (29) Locomotory cilia not as above 31 



31 (30) Cell loricate, sessile. Family FOLLICULINIDAE. 



31 (30) Cell aloricate, generally free-swimming. 



15 



