Phacus pyrum or P. rudicula, a small euglenoid flagellate having a pyriform rigid pellicle thrown into folds (P. pyrum is described as round in cross section while P. rudicula is said to be more flattened as is the cell shown here, but it is likely the two are different forms of the same species). With oblique ridges and tapering, pointed posterior. Red stigma. These individuals have shed their flagella which are usually about 1½ body length. From freshwater pond near Boise, Idaho. Oblique illumination.
