EUGLENOIDINA 241 



P. granuUfera Penard. Much smaller, 8-15/i long; spherical or 

 elongate; pelhcle granulated; standing water. 



Genus Petalomonas Stein, Colorless; constant in form; pellicle 

 often with longitudinal keels on one side; a single flagellum; ho lo zoic 

 or saprozoic; cytostome at anterior end; cytopharynx fairly deep; 

 in fresh water, rich in vegetable matter. Many species. 



P. medio canellata S. (Fig. 103, e). Ovoid with longitudinal furrow; 

 flagellum about as long as body; 22-23 /x long. 



Genus Menoidium Perty. Rigid body, more or less curved; pellicle 

 striated ; a single flagellum ; fresh water. 



M. incurvum (Fresenius) (Figs. 24, d; 67; 103, /). Crescentic cyl- 

 inder; flagellum as long as body; nucleus central or terminal; 15- 

 25/i by 7-8^; in standing fresh water. Hall (1923) made a careful 

 cytological study of the organism (p. 144). 



M. tortuosum Stokes. S-form; posterior end drawn out to a sharp 

 point; elongate paramylon bodies; 42-78/1 long; in infusion. 



Genus Scytomonas Stein. Oval or pyrrform, with a delicate pel- 

 licle; a single flagellum; a contractile vacuole with a reservoir; 

 ho lo zoic on bacteria; longitudinal fission in motile stage; stagnant 

 water and coprozoic. 



S. pusilla S. (Fig. 103, g). About 15/x long. 



Genus Copromonas Dobell. Elongate ovoid; with a single flagel- 

 lum; a small cytostome at anterior end; ho lo zoic on bacteria; per- 

 manent fusion followed by encystment (p. 151); coprozoic in faecal 

 matters of frog, toad, and man; several authors hold that this genus 

 is probably identical with Scytomonas which was incompletely de- 

 scribed by Stein. 



C. subtilis D. (Fig. 73). 7-20^ long. 



Family 3 Anisonemidae Schewiakoff 



Colorless body plastic or rigid with a variously marked pellicle; 

 2 flagella, one directed anteriorly and the other usually posteriorly; 

 contractile vacuoles and reservoir; stigma absent; paramylon bodies 

 usually present; free-swimming or creeping. 



Genus Anisonema Dujardin. Generally ovoid; more or less flat- 

 tened; asymmetrical; plastic or rigid; a slit-like ventral furrow; 

 flagella at anterior end; cytopharynx long; contractile vacuole an- 

 terior; nucleus posterior; in fresh water. Several species. 



A. acinus D. (Fig. 103, h). Rigid; oval; somewhat flattened; pel- 

 licle slightly striated; 25-40^ by 16-22^. 



A. truncatum Stein (Fig. 103, i). Rigid; ovoid; 60/i by 20/x. 



A. emarginatum Stokes (Fig. 103, j). Rigid; 14/i long; flagella long. 



