404 BIOLOGY OF THE PROTOZOA 



19a. Ectoparasites on fresh water fish. . .Genus Ichthyophthirius 

 Free living, not parasitic (Fig. 166, p. 379) 



Genus Holophrya 



20. Body flask-shape (Fig. 166, p. 379) . Genus Enchelys 

 Body elhpsoidal Genus Lagynus 



21. With ventral non-ciliated adhesive disc 



Genus Balantidiopsis 

 Flask-shape, no adhesive disc (Fig. 90, 



p. 181) Genus Spathidium 



22. Two to four small oral tentacles; girdle 



median (Fig. 163, p. 372) Genus Mesodinium 



Without oral tentacles 23 



23. With one girdle of powerful cilia 24 



More than one girdle of long cilia 25 



24. Body cilia not appreciably reduced (Fig. 



(166, p. 379) Genus Cyclotrichium 



Cilia reduced to small lateral area (Fig. 



7.5, p. 146) Genus Monodinium 



25. With two girdles of long cilia 26 



More than two girdles of cilia Genus Dinophrya 



26. Body cilia in addition to girdles (Fig. 75, 



p. 146 Genus Askenasia 



With girdles only, no other cUia (Fig. 89, 



p. 180) Genus Didinmm 



Family 3. Chlamydodontidae, Stein. 



1. Body ellipsoid or slightly compressed 2 



Body lens-shape or ventrally flattened .... 3 



2. Body covered with uniform cilia (Fig. 13, 



p. 35) Genus Nnssula 



With spiral, ciliated narrow groove. Genus Trichospira 



3. Body lens-shape 4 



Body flattened 5 



4. Mouth anterior with corneous, curved, tube 



Genus Pseudomicrothorax 

 Tube similar, bundle of long cilia from 



mouth Genus Leptopharynx 



5. Body without caudal appendage 6 



Body with caudal appendage 11 



6. With small anterior tentacle; mouth ques- 



tionable Genus Lophophorina 



Without anterior tentacle 7 



7. Mouth and trichites in anterior half of body 8 

 Mouth anterior (?) trichites posterior to 



center (Fig. 166, p. 379) Genus Opisthodon 



8. Mouth a transverse slit across enthe body 



Genus Gastronauia 

 Mouth circular 9 



9. Body with cross-striped band around edge 



Genus Chlamydodon 

 Body without cross-striped band 10 



10. Mouth on right side of anterior angle (Fig. 



83, p. 158) Genus Orthodon 



Mouth central or toward right side (Fig. 



34, p. 77) Genus Chilodon 



1 1 . Caucial appendage a ciliated brush . . Genus Trichopus 

 Caudal appendage a spine-like process. ... 12 



