HOLOTRICHA 571 



C. (Urotricha) lahiata (Edmondson) (Fig. 271, i). Body ovoid; 

 a lip-like process in front of cytostome; macronucleus oblong, central; 

 contractile vacucle terminal; 30^ long; fresh water. 



Genus Platyophrya Kahl. Compressed; flask-like or elongate 

 ovoid; asymmetrical; dorsal surface convex, ventral surface flat or 

 partly concave; spiral striation; position and direction of cytostome 

 variable; macronucleus round; contractile vacuole terminal; fresh 

 water. 



P. lata K. (Fig. 271, j). Highly compressed; colorless; many 

 striae; on left edge of cytostome 5-6 cirrus-like projections and on 

 right edge manyshort bristles; lOSju long; freshwater with sphagnum. 



Genus Stephanopogon Entz. Somewhat resembles Platyophrya; 

 compressed; cytostome at anterior extremity which is drawn out; 

 cytostome surrounded by lobed membranous structures; salt water. 



S. colpoda E. (Fig. 271, k). Longitudinal striae on 'neck' 4-8 in 

 number; 2 contractile vacuoles; 50-70m long; creeping movement; 

 salt water among algae. 



Genus Prorodon Ehrenberg (Rhagadostoma Kahl). Ovoid to 

 cylindrical; ciliation uniform, with sometimes longer caudal cilia; 

 oral basket made up of double trichites which end deep in ectoplasm, 

 oval in cross-section; contractile vacuole terminal; macronucleus 

 massive, spherical or oval ; fresh or salt water. Numerous species. 



P. discolor (E.) (Fig. 271, I). Ovoidal; 45-55 ciliary rows; macro- 

 nucleus ellipsoid; micro nucleus hemispherical; contractile vacuole 

 terminal; 100-130/i long; fresh water; Kahl (1930) states that it oc- 

 curs also in brackish water containing 2.5 per cent salt; sapropelic 

 form in salt water is said to possess often long caudal cilia. 



P. griseus Claparede and Lachmann. Oblong; 165-200^ long; 

 fresh water. 



Genus Pseudoprorodon Blochmann. Similar to Prorodon; usually 

 flattened; one side convex, the other concave; ectoplasm conspicu- 

 ously alveolated; trichocysts grouped; 1 or more contractile vacu- 

 oles posterior-lateral or distributed, with many pores; macronucleus 

 elongate; cytopharynx with trichites; fresh or salt water. 



P. farctus (Claparede and Lachmann) (Figs. 21, h; 271, m). Ellip- 

 soid; cytostome surrounded by long trichites; contractile vacuole 

 posterior, with secondary vacuoles; macronucleus elongate; body 

 150-200m long; fresh water. 



Genus Placus Cohn (Spathidiopis Fabre-Domergue; Thoraco- 

 phrya Kahl). Body small; ellipsoid or ovoid; somewhat compressed; 

 pellicle with conspicuous spiral furrows; cytostome a narrow slit at 

 anterior extremity; with strong cilia on right margin of slit; cytopyge 



