|  Family: Paoral membrane prominent, may be large and may project stiffly (Carey, 1992). Genus:  Ovoid to ellipsoid; peristome begins at anterior end and extends for 2/3 the body length; 
a conspicuous membrane at both edges; one to many posterior stiff sensory cilia 
(Kudo, 1966).  Swimming as leaping movement.
 Species:
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