38 (37) Three peniculi winding across buccal cavity floor 39 



%gss 



k 



% 



38 (37) One to three short longitudinal peniculi on left side of buccal cavity. 

 Family FRONTONIIDAE. 



39 (38) Buccal cavity semispherical. Family OPHRYOGLENIDAE. 



39 (38) Buccal cavity tubular, preceded by ciliated vestibulum. Family PARAME- 

 CIIDAE. 



40 (37) Postbuccal ciliary rows present. Buccal cavity round to triangu- 

 lar, in anterior one-half of body. Undulating membrane L- 

 shaped. Three buccal membranelles perpendicular to long axis 

 of body 41 



40 (37) No postbuccal ciliary rows. Buccal cavity elongate; cytostome 

 often at or posterior to middle of body. Undulating membrane 

 various. Other buccal cilia in various groups different from 

 above 42 



18 



