MORPHOLOGY AND TAXONOMY OF THE INFUSORIA 515 



Family 4. Ophryoscolecidae Stein 1858. 



7. Forms with one skeletal plate S 



Forms with more than one skeletal plate. . 10 



8. Skeletal plate narrow 9 



Skeletal plate very broad beneath the right 



surface of the body Genus Ostracodinium Dogiel 



9. Forms with triangular or rod-like macro- 



nucleus; anterior end often bent ven- 



trally Genus Eremoplastron 



Kof. and MacL. 

 Rod-like macronucleus with anterior end 

 bent into a hook dorsally Genus Eudiplodinium Dogiel 



10. Forms with 2 skeletal plates 11 



Forms with more than 2 skeletal plates. . . 12 



11. Macronucleus narrow and rod-like. .Genus Diploplastron 



Kof. and MacL. 

 Macronucleus large with 2 or 3 dorsal lobes 



Genus Metadinium Awerinzew 

 and Mutafowa 



12. Three skeletal plates beneath right ventral 



surface Genus Enoploplastron 



Kof. and MacL. 

 More than 3 skeletal plates 13 



13. Four skeletal plates; 2 right, 1 left and 



1 ventral Genus Elyptroplastron 



Kof. and MacL. 

 Five skeletal plates; 2 right and 3 left 



Genus Poly plastron Dogiel 

 11. Dorsal zone short and far posterior. .Genus Opisthotrichum Buisson 

 Dorsal zone slightly below adoral zone. . . 15 



15. Dorsal zone encircling less than half the 



body Genus Epidinium Crawley 



Dorsal zone encircling more than half the 

 body 16 



16. Dorsal zone encircling four-fifths of the 



body Genus Ophryoscolex Stein 



Dorsal zone entirely encircling body . Genus Caloscolex Dogiel 

 Family 5. Cycloposthiidae Poche 1913. 



1 . Posterior cirri in tufts (caudalia) 2 



Posterior cirri in rows 6 



2. Forms with 2 caudalia 3 



Forms with more than 2 caudalia 5 



3. Forms having a spherical macronucleus 



Genus Bozasella Buisson 

 Forms having an elongate macronucleus . . 4 



4. Body barrel-shaped ; caudalia posterior and 



level Genus Cycloposthium Bundle 



Body helmet-shaped ; caudalia at different 



levels Genus Triadinium Fiorentini 



5. Forms with 2 dorsal caudalia and 1 ventral 



Genus Tripalmaria Gassowsky 

 Forms with 3 dorsal caudalia and 1 ventral 



Genus Protoapirella Cunha 



6. Forms with adoral zone and 2 rows of more 



posterior membranelles 7 



Forms with more than 2 rows of posterior 

 membranelles 8 



