3 (2) Cytostome apical, lateral, or ventral on cell surface 

 or in depression. Free-living or endocommensal. . . 



'•'>',' j'''i 



3 (2) Cytostome absent. Cell oval-elongate, living in various 

 invertebrates 



24 



;//;;;/.'; 



4 (3) Cytostome apical; circular or slitlike. 



4 (3) Cytostome lateral or ventral 11 



5 (i) Cytostome at base of ciliated apical vestibulum. Family 

 COELOSOMIDIDAE. 



5 (4) Cytostome on general cell surface or at 

 base of nonciliated depression 



