KEY TO FAMILIES AND MARINE GENERA OF EUGLENIDA.

1. With deeply-insunk pharynx; 2
no mouth

With pharynx and distinct mouth Family _Peranemidæ_

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

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

Family _Euglenidæ_:

Body _Euglena_-like, inclosed Genus _Trachelomonas_
in shell with round opening for
exit of flagellum

Family _Astastidæ_:

Body with one flagellum Genus *_Astasia_

Family _Peranemidæ_:

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