512 BIOLOGY OF THE PROTOZOA 



Family 7. Folliculinidae Dons 11)12. 



2. Posterior end and sides of test with sack- 



like protuberances ( renus Mirofolliculina Dons 



Tests without protuberances 3 



3. Tests attached on broad surface; neck 



oblique Genus Folliculina Lamarck 



Tests attached at posterior end; tests up- 

 right 4 



4. Test narrow, no central annular furrow 



Genus Pseudofolliculina Dons 

 Test plump, with central furrow; neck 



appears as a short collar Genus Pebrella Giard 



Family 8. Bursariidae Perty 1852. 



1. Posterior end of peristome straight; para- 



sitic 2 



Posterior end of peristome bends to right or 

 left; free-living 3 



2. Peristome opening a narrow slit. . . .Genus Balantidiopsis Biitschli 

 Peristome opening medium wide. . .Genus Balantidium 



Clap, and Lach. 



3. Posterior end of peristome funnel bends to 



left. 4 



Posterior end of peristome funnel bends to 



right Genus Bursaridium Lauterborn 



4. Very large animals with longitudinal fold 



(tongue) dividing peristomial space in 



two sections Genus Bursaria 0. F. M. 



Medium or small forms with simple peris- 

 tome Genus Thylacidium Schewiakoff 



Family 9. Peritromidae Stein 1867. 



1. Ventral surface flat; adoral zone semicir- 

 cular around anterior left margin. Genus Peritromus Stein 

 Flat surface bent dorsally; anterior to 

 mouth a peristome-like area with meri- 

 dional fibers to mouth Genus Pediostomum 



Faure-Fremiet 

 Family 10. Lichnophoridae Stevens 1903. 

 One genus only — Lichnophora Claparede 



Order 2. OLIGOTRICHIDA Butschli 1889. 



Key to Families 



1. Free-living forms 2 



Endocommensal forms 4 



2. Oral part of peristome lies free on ventral 



surface Family 1. Halteriidae 



Adoral zone encircles frontal field and 

 mouth region 3 



3. No house or test Family 2. Strombilidiidae 



House or test present Family 3. Tintinnidae 



4. With one or two rings of membranelles 



directed forwards Family 4. Ophryoscolecidae 



With additional bundles of cirri directed 

 backwards Family 5. Cycloposthiidae 



