POLYMASTIGINA 371 



Dallingeria, but anterior region not constricted; 3 flagella from an- 

 terior end; one contractile vacuole; fresh water. 



M. lapsa S. (Fig. 154, c). Ovoid; 5.5/x long; anterior flagellum 1/2 

 and trailing flagella 2-3 times body length; pond water. 



Genus Mixotricha Sutherland. Large; elongate; anterior tip 

 spirally twisted and motile; body surface with a coat of flagella in 

 closely packed transverse bands (insertion and movement entirely 

 different from those of Trichonympha) except posterior end ; 3 short 

 flagella at anterior end; nucleus, 20m by 2ju, connected with blepharo- 

 plasts by prolonged tube which encloses nucleus itself; cytoplasm 

 with scattered wood chips; in termite gut. One species. Taxonomic 

 position undetermined. 



M. paradoxa S. About 340^ long, 200> broad and 25/x thick ; in gut 

 of Mastotermes darwiniensis ; Australia (Sutherland). 



Family 2 Tetramitidae Butschli 



Genus Tetramitus Perty. Ellipsoidal or pyriform; free-swimming; 

 cytostome at anterior end; 4 flagella unequal in length; a contractile 

 vacuole; holozoic; fresh or salt water or parasitic. Species (Klug, 

 1936). 



T. rostratus P. (Fig. 15G, a). Body form variable, usually ovoid and 

 narrowed posteriorly: 18-30ju by 8-11 n; stagnant water. Bunting 

 (1922, 1926) observed an interesting life cycle of what appeared to be 

 this organism which she had found in cultures of the caecal content 

 of rats (Fig. 155). Nuclear division (Bunting and Wenrich, 1929). 



T. pyriformis Klebs (Fig. 156, b). Pyriform, with pointed poste- 

 rior end; 11-13/x by 10-1 2/x; stagnant water. 



T. salinus (Entz) (Fig. 156, c). 2 anterior flagella, 2 long trailing 

 flagella; nucleus anterior; cytostome anterior to nucleus; a groove to 

 posterior end; cytopharynx temporary and length variable; 20-30^ 

 long (Entz); 15-19ju long (Kirby). Kirby observed it in a pool with 

 a high salinity at Marina, California. 



Genus Collodictyon Carter. Body highly plastic; with longitudinal 

 furrows; posterior end bluntly narrowed or lobed; no apparent 

 cytostome; 4 flagella; a contractile vacuole anterior; fresh water. 



C. triciliatum C. (Fig. 156, d). Spherical, ovoid or heart-shaped; 

 27-60/x long; flagella as long as the body; pond water. Cytology 

 (Rhodes, 1919); food ingestion (Belaf, 1921). 



Genus Costia Leclerque. Ovoid in front view, pyriform in profile; 

 toward the right side, there is a shallow depression which leads into 

 cytostome (?) and from which extend two long and two short flagella 

 (only two flagella (Andai, 1933)); contractile vacuole posterior; en- 

 cystment ; ectoparasitic in freshwater fishes. 



