304 PROTOZOOLOGY 



Genus Peranema Dujardin. Elongate, with a broad rounded or 

 truncate posterior end during locomotion; highly plastic when sta- 

 tionary; delicate pellicle shows a fine striation; expansible cytostome 

 with a thickened ridge and two oral rods at anterior end; aperture 

 through which the flagella protrude is also at anterior end; a free 

 flagellum, long and conspicuous, tapers toward free end; a second 

 flagellum adheres to the pellicle; nucleus central; a contractile vacu- 

 ole, anterior, close to the reservoir; holozoic; fresh water. 



P. trichophorum (Ehrenberg) (Fig. 123, d). 4.0-70/x long; body or- 

 dinarily filled with paramylon or starch grains derived from Astasia, 

 Rhabdomonas, Euglena, etc., which coinhabit the culture; holozoic; 

 very common in stagnant water. Cell inclusion (Hall, 1929); struc- 

 ture and behavior (Chen, 1950); development (Lackey, 1929); flag- 

 ellar apparatus (Lackey, 1933; Pitelka, 1945); food intake (Hall, 

 1933; Hollande, 1942; Hyman, 1936; Chen, 1950). 



P. granulifera Penard. Much smaller in size. 8-1 5ju long; elongate, 

 but plastic; pellicle granulated; standing water. 



Genus Heteronema Dujardin. Plastic; rounded or elongate; 

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

 trailing; cytostome near base of flagella; holozoic; fresh water. Sev- 

 eral species. 



H. acus (Ehrenberg) (Fig. 123, e). Extended body tapers towards 

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

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

 Morphology, reproduction (Loefer, 1931). 



H. mutabile (Stokes) (Fig. 123,/). Elongate; highly plastic ; longi- 

 tudinally striated; about 254/x 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. 123, g). 35-63yu 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. Several species (Prings- 

 heim, 1942). 



D. proteus E. (Fig. 123, h). 50-1 10m long when extended; nucleus 

 central; stagnant water; infusion. Cytology (Hollande, 1937). 



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

 flagella arise from a cytostome, one flagellum trailing; protrusible 

 cytopharynx a long conical tubule almost reaching posterior end; 



