54 Fresh-water Biology 



CILIATA 



1 — Body more or less uniformly ciliate, in few cases lacking on one side 2 



— Cilia restricted to a part of the body 11 



2 — Mouth without a definite spiral zone of cilia 3 



— Mouth surrounded by a zone of large cilia. Body more or less funnel shaped (fig. 7), 

 Stentor; body purse shaped Bursaria 



3 — With shell composed of several pieces (fig. 8) Coleps 



—Without shell 4 



4 — With a broad ring like band of cilia Urocentrum 



— With cilia on ventral surface only 5 



— With cilia uniform over whole body 6 



5 — Pharynx basket like; body flat; mouth on anterior half (fig. 11) Chilodon 



— With long neck, body oval, ending in a short tail Lionotus 



— With anterior end hooklike; body brownish (fig. 12) , Loxodes 



6 — Mouth lateral, in front of middle, with projecting undulating membrane, no peristome 



(fig. 10) Colpodium 



— Without undulating membrane 7 



7 — Mouth nearly terminal. Pharynx not apparent, body ovate (fig. 9), Holophyra; 



pharynx evident, long contractile neck (fig. 13) Lacrymaria 



— Mouth ventral, not terminal 8 



8 — With elongate proboscis 9 



— Without proboscis 10 



9 — Mouth open, pharjmx rodlike (fig. 16) Dileptus 



— jMouth commonly closed; no pharynx. Body with broad clear border. Loxophyllum; 

 body without clear border (fig. 15) Amphlleptus 



10 — Mouth near middle (fig. 20) Paramoecium 



— Mouth surrounded by a furrow extending far backwards (fig. 22), Frontonia; mouth 

 bearing a few long ciUa on its posterior left side Colpoda 



11 — Ventral surface with large cilia; a dorsal zone wound to left 12 



— A dorsal zone wound to right 15 



12 — Body not flattened; with projecting bristles (fig. 17) Halteria 



— Body more or less flat; cilia in groups 13 



13 — With many cilia on margin 14 



— No marginal cilia (fig. 18) Euplotes 



14 — Five or more longitudinal rows of ventral cilia Urostyla 



— Five ventral cilia. No caudal bristles, body flexible, Oxytricha; usually three caudal 

 bristles (fig. 24), Stylonychia; two rows of ventral cilia, 3 sternal and no anal cilia 

 Uroleptus 



15 — With chitinous lorica (case) ; unstalked or with short stalk Cothurnia 



— No lorica 16 



16 — Disclike, parasitic on Hydra (fig. 23) ... . . Trichodina 



— Stalked forms 17 



17 — Simple retractile stalk (fig. ?8) Vorticella 



— Branched stalk. Each individual contracting separately (fig. 26), Carchesium; stalk 

 not retractile (fig. 27) Epistylis 



MASTIGOPHORA 



1 — With 2 flagella, one in a longitudinal groove projecting backwards, the other in a 

 transverse groove; colored or hyaline. Ceratlum (fig. 17), Peridlnium (fig. 18). 



— With one flagellum set in a collar Choanoflagellata 



— With one more flagella, without collar or furrow 2 



