No. 2.] FRESH-WATER PROTOZOA. 33 



8. Body in a lorica, oval Tetraselmis 



Body not in a lorica 9 



9. With an evident peristome Tetramitus 



Without evident pharynx lO 



10. With three flagella carried forward, the other trailing 



Trichomastix* 

 With four anterior flagella and two f^^gellum-like 

 processes at posterior Hexamitus* 



11. With two flagella 12 



With four flagella Carteria 



12. Attached to a stalk, or in a lorica 13 



Free swimming 14 



13. Upon a long stalk, with two brown chromatophores 



StylochrysaUs 

 Urn-shaped lorica ; attached to algse Chrysopyxis 



14. With band-shaped, brown chromatophores 15 

 With green chromatophores 16 



15. Broad kidney-shaped ; flagella in an anterior fur- 



row ; one chromatophore ; movement lateral .... 



Nephroselmis 

 Elongated, acute posteriorly; two chromatophores 



and a thick cuticle ; pharynx not evident Ochromonas*^ 

 Elongated, laterally compressed, with evident pharynx 



Cryptomonas* 



16. Spherical 17 



Not spherical 18 



17. With delicate, closely attached cuticle; spherical to 



elliptical ; one chromatophore Chlamydonionas* 



With delicate cuticle, separate from the mass of the 



body Hccmotococcus* 



With rough cuticle, separate from the mass of the 



body Coccomonas 



18. Lenticular, with a two-valved cuticle Phacotus 



Elongated, spindle-shaped ; two ribbon-like chroma- 

 tophores Chlorangium* 



Spindle-shaped; body uniformly green. . . .Chlorogonium 



19. Uncolored 20 



Colored ' 21 



