Family Bodonidae: 

   1.  Body very plastic, Genus *_Bodo_
      almost amoeboid

      Body not plastic; with large Genus *_Oxyrrhis_
      anterior cavity, holding flagella

Family Trimastigidae: 

   1.  With an undulatory membrane Genus Trimastix
      between accessory flagella

      Without such membrane; flagella Genus Costia
      contained in a ventral groove
      while at rest

   * Presence at Woods Hole indicated by asterisk.

KEY TO MARINE GENERA OF POLYMASTIGIDA.

   1.  Body flattened; ends rounded; Genus Trepomonas
      sides hollowed; often with
      wing-like processes; cross
      section S-shaped

   2.  Body pyriform; one large Genus Tetramitus
      asymmetrical groove; 4 flagella

   3.  Body spherical; many flagella Genus Multicilia
      equally distributed

KEY TO FAMILIES AND MARINE GENERA OF EUGLENIDA.

   1.  With deeply-insunk pharynx; 2
      no mouth

      With pharynx and distinct mouth Family Peranemidae

   2.  Body plastic; usually with Family Euglenidae
      chromatophores and eye-spot

      Body plastic; no chromatophores; Family Astastidae
      no eye-spot

Family Euglenidae: 

      Body Euglena-like, inclosed Genus Trachelomonas
      in shell with round opening for
      exit of flagellum

Family Astastidae: 

      Body with one flagellum Genus *_Astasia_

Family Peranemidae: 

   1.  Body striped; plastic; Genus Heteronema
      two diverse flagella

   2.  Body striped; not plastic; Genus *_Anisonema_
      posterior flagellum longer
      than the other

   3.  Body striped; not plastic; Genus Entosiphon
      with rod-like organ in pharynx

   * Presence at Woods Hole indicated by asterisk.

Genus MASTIGAMOEBA F. E. Schultze ’75.

(Kent ’81; Buetschli ’86; Klebs ’92; Senn 1900.)

In general the form is oval and either regular in outline or irregular through the presence of many pseudopodia.  One flagellum usually quite large and distinct.  Differentiation of ectoplasm and endoplasm distinct or wanting.  One to several contractile vacuoles.  The pseudopodia are occasionally withdrawn, and the flagellum is the sole means of locomotion.  In some cases the flagellum turns into a pseudopodium, and, conversely, the pseudopodium at one end may become a flagellum (see below).  In some rare cases the ectoplasm secretes a gelatinous mantle.  Reproduction not observed.