Family: Frontoventral cirri scattered on forward, mid- and rear areas of ventrum. Genus: Oral cavity not wide; 2 oval macronuclei; marginal cirri confluent at rear; frontventral cirri not linear; body firm, not laterally flexible (Illustrated Guide, 1985). a large AZM at least 1/2 body length; caudal & transverse cirri present; two ovoid macronuclei (Carey, 1992). Species:

50 μm 100 μm 150 μm; x 400

Histriculus sp., conjugation ?, by Y. Tsukii