SPIROTRICHA, HETEROTRICHA 645 



N. cordiformis (Ehrenberg) (Figs. 79; 304, c). 60-200m by 40- 

 140/1 ; ovoid; micro nucleus behind macro nucleus; no karyophore; 

 in the colon of frogs and toads. Wichterman (1936) studied its life- 

 cycle in Hyla versicolor (p. 160). 



Family 4 Condyle stomidae Kahl 



Genus Condylostoma Bory. Ellipsoid; anterior end truncate, 

 posterior end rounded or bluntly pointed; slightly flattened; peri- 

 stome wide at anterior end and V-shaped, peristomal field not cili- 

 ated; a large membrane on right edge and adoral zone on left; macro- 

 nucleus moniliform; one to several contractile vacuoles often with 

 canal; cytopyge posterior; fresh or salt water. Many species. 



C. vorticella (Ehrenberg) (Fig. 304, d). 100-200/x long; fresh water. 



C. -patens (Miiller). 250-550/x long; salt water; Woods Hole (Cal- 

 kins). 



Family 5 Stentoridae Carus 



Genus Stentor Oken. When extended, trumpet-shaped or cylindri- 

 cal; highly contractile; some with mucilaginous lorica; usually oval 

 to pyriform while swimming; conspicuous peristomal field frontal; 

 adoral zone encircles peristome in a spiral form, leaving a narrow 

 gap on ventral side; the zone and field sink toward cytostome and 

 the former continues into cytopharynx; macro nucleus round, oval or 

 elongated, in a single mass or moniliform; contractile vacuole 

 anterior-left; free-swimming or attached; fresh water. 



*S. coeruleus Ehrenberg (Figs. 14; 304, e). Fully extended body 

 1-2 mm. long; anterior end greatly expanded; the beautiful blue 

 color is due to a pigment, stentorin, lodged in interstriation gran- 

 ules; macronucleus beaded. Burnside (1929) studied its body and 

 nuclear sizes (p. 171). 



S. striatus Barraud-Maskell. Dark bluish green; funnel-shaped; 

 peristomal edge irregularly undulating; striation conspicuous; macro- 

 nucleus beaded; up to 2.2 mm. long. 



S. polymorphus (MiiWer) (Fig. 304,/). Colorless; with zoochlorellae; 

 1-2 mm. long when extended; macronucleus beaded; anterior end 

 expanded. 



S. miilleri (Bory) (Fig. 304, g). Colorless; with zoochlorellae; 2-3 

 mm. long; anterior end expanded; posterior portion drawn out into 

 stalk, often housed in a gelatinous tube; on body surface 3-4 longer 

 and stiff cilia grouped among cilia; macronucleus moniliform. 



*S. roeseli Ehrenberg (Fig. 304, h). 0.5-1 mm. long; anterior end 

 expanded; body surface with groups of longer cilia; posterior por- 



