PROTOMONADINA 291 



R. intestinalis (Wenyon and O'Connor) (Figs. 131, i; 132). Poly- 

 morphic, often pyriform or ovoid with drawn-out posterior end; 4-9m 

 by 3-4)u; cytostome large, about 1/3 the body length ; vesicular nucleus 

 with an endosome near anterior end; anterior flagellum as long as 

 the body; posterior flagellum shorter, but thicker, in or near cyto- 

 stome; cysts pyriform; 4.5-7/i long; a single nucleus and an oblong 

 area surrounded by fibril; commensal in the lumen of human intes- 

 tine; trophozoites and also cysts occur in diarrhoeic faeces; of com- 

 paratively rare occurrence. 



Genus Phyllomitus Stein. Oval; highly plastic; cytostome large 

 and conspicuous; 2 unequal flagella, each originates in a basal gran- 

 ule; apparently no blepharoplast; fresh water or coprozoic. 



r 



^ % ^ 



4 • • 



8 



Fig. 132. Retortanionas intestinalis, X1150. 1-3, living organisms; 

 4, 5, stained trophozoites; 6, a fresh cj^st; 7, 8, stained cysts (1-4, 

 Wenyon and O'Connor; 5, Dobell and O'Connor; 7, Jepps; 6, 8, Kudo). 



P. undulans S. (Fig. 131, j). Ovoid; 21-27/x long; trailing flagel- 

 lum much longer than anterior one; stagnant water. 



Genus Colponema Stein. Body small; rigid; ventral furrow con- 

 spicuous, wide at anterior end; one flagellum arises from anterior end 

 and the other from middle of body; fresh water. 



C. loxodes S. (Fig. 131, k). 18-30^t by lA/j, cytoplasm with refractile 

 globules. 



Genus Cercomonas Dujardin. Biflagellate, both flagella arising 

 from anterior end of body; one directed anteriorly and the other 

 runs backward over body surface, becoming a trailing flagellum; 

 plastic; pyriform nucleus connected with the basal granules of 

 flagella; spherical cysts uninucleate; fresh water or coprozoic. 



C. longicauda D. (Fig. 131, I). Pyriform or ovoid; posterior end 

 drawn out; 18-36m by 9-14//; flagella as long as body; pseudopodia; 

 fresh water and coprozoic. 



