468 BIOLOGY OF THE PROTOZOA 



Family 1 . Arcellidae Schultze. 

 9. Test rigid; chitinous; without foreign 



bodies 10 



Test more or less plastic ; one or more pores 



Genus Cochliopodium 



Hertwig and Less. 



10. Test symmetrical 11 



Test asymmetrical (one species encrusted) 



Genus Lesquereusia Schlumberger 



1 1. Tests circular in cross-section 12 



Tests ellipsoidal in cross-section . . 15 



12. Free-living forms 13 



Parasitic form (Fig. 189) Genus Chlamydophrys 



Cienkowsky 



13. Pseudopodia lobose 14 



Pseudopodia short lobose with aciculate tip 



Genus Difflugiella Cash 



14. Aperture of test with inturned margin 



Genus Arcella Ehr. 

 Margin not inturned; one lobose pseudo- 

 podium Genus Leptochlamys West 



15. Tests yellow or brown; minute; without 



pits 16 



Tests hyaline; transparent; usually with 



pits Genus Hyalosphenia 



1(3. Mouth oval placed obliquely to ventral 



surface Genus Wailesella de Flandre 



Test mouth slit-like, terminal Genus Cryptodifflugia Penard 



Family 2. Difflugiidae. 



1. Test circular in cross-section 2 



Test ellipsoidal in cross-section (com- 

 pressed) 7 



2. Aperture of test circular 3 



Aperture of test ellipsoidal, linear, or tri- 



radiate 6 



3. Aperture without lobed external collar. ... 4 

 Aperture with three- or four-lobed external 



collar Genus Cucurbitella Penard 



4. Aperture excentric in position Genus Centropyxis Stein 



Aperture central ; symmetrical 5 



5. Test covered with diatom shells; pseudo- 



podia pointed Genus Phryganella Penard 



Test covered with sand, mud, detritus, etc. 



( Fig. 190) Genus Difflugia Leclerc 



6. Aperture triangular; inner shell about body 



Genus Cystidina Volz 

 Aperture ellipsoidal Genus Plagiopyxis Penard 



7. Test with constricted neck and internal 



shelf Genus Pontigulasia Rhumbler 



Test without internal shelf 8 



8. Test with foreign particles on dome only. . 9 

 Test covered; aperture a long and narrow 



slit Genus Bullinula Penard 



9. Aperture of test convex Genus Heleopera Leidy 



Aperture small, ellipsoidal, with thickened 



margins Genus Awerintzia Schoutedon 



