POLYMASTIGINA 395 



parts of small intestine and colon of man. Both trophozoites and 

 cysts are ordinarily found in diarrhoeic faeces. In severe cases of in- 

 fection, an enormous number of the organisms attach themselves to 

 the mucous membrane of the intestine which may result in abnormal 

 functions of the host tissues. In some cases, the flagellate has been 

 reported from the gall bladder. The stools often contain unusual 

 amount of mucus. Although there is no evidence that G. intestinalis 

 attacks the intestinal epithelium, experimental observations point to 

 its pathogenicity (Tsuchiya and Andrews, 1930). Cytology (Kofoid 

 and Swezy, 1922). 



G. duodenalis (Davaine). In the intestine of rabbits; 1 3-1 9m by 8- 

 U/x (Hegner, 1922). 



G. canis Hegner. In dogs; 12-17/x by 7.6-10/z; cysts oval, 9- 13m by 

 7-9m (Hegner, 1922). 



G. muris (Grassi). In rats and mice; 7-13m by 5- 10m (Simon, 1922). 



G. simoni Lavier. In the small intestine of rats; 14-19m by 7-10. 5m 

 (Lavier, 1924); 11—16/* by 5-8m (Nieschulz and Krijgsman, 1925). 



G. ondatrae Travis. In the intestine of the muskrat, Ondatra 

 zibethica; 13m by 7m (Travis, 1939); 10m by 5.5m (Waters et al). 



G. caviae Hegner. In the intestine of guinea-pigs; 8-14m by 5.5- 

 10m (Hegner, 1923). 



Genus Trepomonas Dujardin. Free-swimming; flattened; more or 

 less rounded; cytostomal grooves on posterior half, one on each side; 

 8 flagella (one long and 3 short flagella on each side) arise from ante- 

 rior margin of groove; near anterior margin there is a horseshoe-form 

 structure, in which two nuclei are located; fresh water, parasitic, 

 or coprozoic. 



T. agilis D. (Fig. 168, /). More or less ovoid; 7-30m long; 1 long 

 and 3 short flagella on each side; rotation movement; stagnant 

 water; also reported from intestine of amphibians. 



T. rotans Klebs (Fig. 168, g). Broadly oval; posterior half highly 

 flattened; 2 long and 2 short flagella on each of 2 cytostomes; stag- 

 nant water. ' 



Genus Gyromonas Seligo. Free-swimming; small; form constant, 

 flattened; slightly spirally coiled; 4 flagella at anterior end; cyto- 

 stome not observed; fresh water. 



G. ambulans S. (Fig. 168, h). Rounded; 8-15m long; standing 

 water. 



Genus Trigonomonas Klebs. Free-swimming; pyriform, plastic; 

 cytostome on either side, from anterior margin of which arise 3 

 flagella; flagella 6 in all; 2 nuclei situated near anterior end; move- 

 ment rotation; holozoic; fresh water. 



