126 HANDBOOK OF PROTOZOOLOGY 



Heteronema acus (Ehrenberg) (Fig. 42, g). Extended body 

 tapers towards both ends. Anterior flagellum as long as the 

 body, the trailing one about one-half. Contractile vacuole near 

 the anterior end ; nucleus central. About 30 to 80 microns long. 

 Fresh water and soil. 



Genus Distigma Ehrenberg. Plastic; elongated when ex- 

 tended. Body surface without any marking. Two flagella 

 unequal in length, directed forward. Cytostome and cyto- 

 pharynx located at the anterior end. Endoplasm transparent. 

 Holozoic. Fresh water; especially stagnant water, infusion, etc. 



Distigma proteus (Stein) (Fig. 42, h). Longer flagellum 

 about as long as the body, the other about one-half. Nucleus 

 central; contractile vacuole anterior. When extended, about 

 100 microns long. 



Genus Entosiphon Stein. Body more or less rigid; oval, 

 flattened. Flagella arise from a cytostome at the anterior end. 

 One flagellum trailing. The protrusible cytopharynx is a long 

 conical tubule almost reaching the posterior end. The nucleus 

 central and toward one side. 



Entosiphon sulcatum (Dujardin) (Fig. 42, i). Body about 

 20 microns long. Fresh water and infusion. 



Genus Anisonema Dujardin. Body as a rule oval, more or 

 less flattened and asymmetrical. A slit-like ventral furrow. 

 The flagellum arises from the anterior end. Cytopharynx 

 long; contractile vacuole anterior; nucleus posterior. Fresh 

 water. 



Anisonema acinus Dujardin (Fig. 42, /). Body about 55 

 microns long. 



Anisonema truncatum Stein (Fig. 42, k). Body about 40 

 to 45 microns long. 



Anisonema emarginata Stokes (Fig. 42, /). Body about 15 

 microns long. 



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

 Ventral surface convex, dorsal surface with a broad longitud- 

 inal groove. Two flagella arise from the anterior end; one long, 

 directed anteriorly and vibratile; the other shorter and trail- 

 ing. Colorless. 



Notosolenus apocamptus Stokes (Fig. 42, m). Body up to 

 10 microns in length. 



