Trinema enchelys (Ehrenberg, 1838) Leidy, 1878

Diagnosis: Shell ovoid and flattened slightly in the apertural region, composed of approximately fifty, large, circular, incompletely overlapping scales and an unknown number of smaller, oval, scales. Aperture circular, sub-terminal and invaginated, bordered by an inner circle of about forty apertural scales, and two or three rows of small, oval, scales. Each apertural scale is circular, and carries a median, dorsal tooth. One to two contractile vacuoles; pseudopodia few, attenuate and long.

Dimensions: 44—100 um long; 15—60 µm wide; scales 4—12 µm in diameter.  diameter of large shell-scales 5.6—10.3, diameter of small shell-scales 1.9—4.3; diameter of apertural scales 0.9—1.8 µm.

Habitat: Common in mosses, soil and aquatic vegetation.

Remarks: Distinction between T. enchelys and the very similar T. lineare only by their size. Both Chardez (1956) and Thomas (1958) have shown the differences in shape and size of the shell of this species.