Flagellata is an order of Protozoa characterized by the presence of flagellae (whip-like structures used for locomotion). In many flagellate forms, chlorophyll is present. These forms have been regarded by botanists as minute algae. This illustration shows 3 flagellates: 1) Ceratium Tripos, 2) Noctiluca, and 3) Euglena.
John H. Finley ed. Nelson's Perpetual Loose-Leaf Encyclopaedia (vol. 5) (New York, NY: Thomas Nelson and Sons, 1917)