short and hard to make out. The body is usually covered uniformly
with trichocysts, often of considerable size. There are 1 or 2
vacuoles with long canals radiating throughout the endoplasm. The
macronucleus is oval and centrally placed. Micronuclei vary from
one to many. An anal opening is placed at the end of the long
ventral furrow. The plasm is colorless or green by the presence of
Zoochlorella, or colored brown or black by pigments. In these cases
there is a considerable pigment mass on the anterior end. Movement
is regular, forward, and combined with rotation. Food consists of
foreign objects, diatoms, other protozoa and the like. Fresh and salt
water.


Frontonia leucas Ehr. Fig. 37.

Synonyms: _Frontonia vernalis_ Ehr. '38; _Bursaria leucas_ Allman
'55, Carter '56; _Panophrys leucas_ Duj. '41, Stein '67; _Panophrys
vernalis_ Dujardin '41, Stein '67; _P. chrysalis_ Duj. '41, Fromentel
'74; _Cyrtostomum leucas_ Stein '67, Kent '81.

Form ovoid, elongate, occasionally a little flattened
dorso-ventrally. Mouth in the anterior third of the body. The left
edge of the mouth carries a distinct undulating membrane; the right
edge is plain, longitudinally striated and bears cilia. It is
slightly depressed and the depression is carried posteriorly in the
form of a shallow furrow which reaches to the posterior end. The
contractile vacuole is on the left side, the spheroidal nucleus on
the right side of the furrow. The body is uniformly covered with fine
cilia, and the periphery is uniformly studded with large trichocysts,
except along the furrow. Food consists of dinoflagellates and other