Optical section (right lateral view) of the prorodontid ciliate, Placus luciae (Kahl,1926) Kahl,1930. The cell is ovoid and slightly laterally compressed. The pellicle has broad slightly spiral ridges separated by narrow furrows. The small oval oral aperture is apical anterior, surrounded by a ring of unciliated kinetosomes. The cytopharynx is supported by fine trichites. The somatic ciliature uniform, with cilia. There is a "brush" composed of a double parallel row of kinetosomes bearing longer cilia. This is about 1/4 to 1/3 cell length arising adjacent to the oral aperture. It terminates at a ventral circular "pit" (seen here as a slight depression anteriorly on viewer's right) which has a supporting ring of transversely oriented trichites (faintly visible here). the function of this structure is unknown . The ovoid macronucleus is centrally located. The contractile vacuole is posterolateral (seen in this image). Collected from a slow-flowing freshwater stream near Boise, Idaho. DIC.