WAcotylea
WCatenulidae
WCercyridae
WCotylea (worm)
WDalytyphloplanida
WDolichomacrostomidae
WEuryleptidae
WHumbertium
WKalyptorhynchia
WLecithoepitheliata
WMacrostomidae
WMaritigrella fuscopunctata
WMonocelididae
WMüller's larva
WPlanaria
WProsthiostomidae
WPseudobiceros
WPseudobiceros gloriosus
WPseudoceros
WPseudoceros bifurcus
WPseudoceros dimidiatus
WPseudoceros ferrugineus
WPseudoceros lindae
WPseudoceros monostichos
WPseudoceros susanae
WPseudocerotidae
WSalinella
WSchmidtea
WStenostomidae
WThysanozoon
WUteriporinae
WYungia