242 PROTOZOOLOGY 



Genus Heteronema Dujardin. Plastic; rounded or elongate; 

 flagella arise from anterior end, one directed forward and the other 

 trailing; cytostome near base of flagella; ho lo zoic; fresh water. Sev- 

 eral species. 



H. acus (Ehrenberg) (Fig. 103, k). Extended body tapers towards 

 both ends; anterior flagellum as long as body, trailing one about 1/2; 

 contractile vacuole anterior ; nucleus central ; 45-50/x long ; fresh water. 



H. mutahile (Stokes) (Fig. 103, I). Elongate; highly plastic; longi- 

 tudinally striated; about 254;u long; in cypress swamp. 



Genus Tropidoscyphus Stein. Slightly plastic; pellicle with 8 

 longitudinal ridges; 2 unequal flagella at anterior pole; holozoic or 

 saprozoic; fresh or salt water. 



T. octocostatus S. (Fig. 103, m). 35-63m long; fresh water, rich in 

 vegetation. 



Genus Distigma Ehrenberg. Plastic; elongate when extended; 

 body surface without any marking; 2 flagella unequal in length, di- 

 rected forward; cytostome and cytopharynx located at anterior end; 

 endoplasm usually transparent; holozoic. One species. 



D. proteus E. (Fig. 103, n). 50-1 lO/x long when extended; nucleus 

 central; stagnant water; infusion. 



Genus Entosiphon Stein. Oval, flattened; more or less rigid; 

 flagella arise from a cytostome, one flagellum trailing; protrusible 

 cytophar3^nx a long conical tubule almost reaching posterior end; 

 nucleus centro -lateral; fresh water. 



E. sulcatum (Dujardin) (Fig. 103, o). About 20/i long. 



E. ovatum Stokes. Anterior end rounded; 10-12 longitudinal 

 striae; about 25-28/i long. 



Genus Notosolenus Stokes. Free-swimming; rigid oval; ventral 

 surface convex, dorsal surface with a broad longitudinal groove; 

 flagella anterior; one long, directed anteriorly and vibratile; the 

 other shorter and trailing; fresh water with vegetation. 



N. apocamptus S. (Fig. 103, p). Oval with broad posterior end; 

 6-1 Iju long. 



N. sinuatus S. (Fig. 103, q). Posterior end truncate or concave; 

 about 22/i long. 



Genus Marsupiogaster Schewiakoff. Oval; flattened; asymme- 

 trical; cytostome occupies entire anterior end; cytopharynx con- 

 spicuous, 1/2 body length; body longitudinally striated; 2 flagella, 

 one directed anteriorly, the other posteriorly; spherical nucleus; 

 contractile vacuole anterior; fresh or salt water. 



M. striata Schewiakoff (Fig. 103, r). About 27m by 15^; fresh 

 water; Hawaii. 



