Large; firm body wall; 1 or 2 flagella; Order EUGLENIDA.
mouth or pharynx, or both

Medium size; with chlorophyll, Order PHYTOFLAGELLIDA.
no mouth, usually colonial

Small; silicious skeleton; parasitic Order SILICOFLAGELLIDA.
on Radiolaria or free (One genus,
_Distephanus_ Stöhr)


KEY TO THE FAMILIES OF MONADIDA.

No mouth; 1 or 2 flagella: amoeboid Family _Rhizomastigidæ_
with lobose or ray-like pseudopodia

Mouth at base of single flagellum; Family _Cercomonadidæ_
plastic; no pseudopodia

One flagellum; inclosed in gelatinous Family _Codonoecidæ_
or membranous cups

One flagellum; tentacle like process Family _Bikoecidæ_
at base of flagellum; inclosed in cup

One main flagellum and 1 or 2 Family _Heteromonadidæ_
accessory flagella


KEY TO MARINE GENERA OF MONADIDA.*