|  Genus: Cigar- or foot-shaped; a single macronucleus and 1 to several vesicular or compact microuclei 
(Kudo, 1966). Species: Oblong; 50-105 (80-90) μm long; 
a compact micronucleus; two contractile vacuoles; fresh water (Kudo, 1966).  
Similar in shape to P. bursaria but much more rounded at both ends; 
70-90 μm long; 
two conctractile vacuoles; a single ovoid macronucleus with a single micronucleus; caudal cilia present 
(Carey, 1992).
 Generally believed P. trichium = P. putrinum (see below)
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