PROTOMONADINA 



343 



vesicular nucleus median; a contractile vacuole terminal; individuals 

 are enclosed in arboroid, dichotomously branching tubes; fresh 

 water. 



S. dichotoma L. (Fig. 140, a). Body ovoid, 10m by 8m; flagellum up 

 to 25/x long; collar 12m long; the dichotomous tube infolded and 

 wrinkled where branched; organisms are not attached to the tube 

 (Lackey, 1942). 



Fig. 140. a, Stelexomonas dichotoma, X1000 (Lackey); b, Oikomonas 

 termo, X1330 (Lemmermann) ; c, Thylacomonas compressa, X640 (Lem- 

 mermann); d, Ancyromonas contorta, X2000 (Lemmermann); e, Platy- 

 theca microspora, X650 (Stein): f, Aulomonas purdyi, X1000 (Lackey); 

 g, Caviomonas mobilis, X2400 (Nie). 



Family 4 Oikomonadidae Hartog 



Genus Oikomonas Kent. A rounded monomastigote; uninucleate; 

 encystment common; stagnant water, soil and exposed faecal mat- 

 ter. Several workers note the affinity of the members of this genus 

 with Chrysomonadina, on the basis of general structure, cyst, etc., 

 though lacking chromatophores. Owen (1949) points out the flagel- 

 lum of Oikomonas is a simple one, typical of Chrysomonadina. 



0. termo (Ehrenberg) (Fig. 140, b). Spherical or oval; anterior end 

 lip-like; flagellum about twice body length; a contractile vacuole; 

 5-20m in diameter; stagnant water. Bacteria-free culture (Hardin, 

 1942); bacterial food (Hardin, 1944, 1944a). 



Genus Thylacomonas Schewiakoff. Pellicle distinct; cytostome 



