WBellinuridae
WCarcinosomatidae
WCascoplecia
WDinopanorpidae
WDolichopteridae
WEncrinuridae
WEophrynidae
WEuphoberiidae
WEurypteridae
WEuthycarcinoidea
WHardieopteridae
WKokomopteridae
WEuthycarcinoidea
WLatzelia
WLiwiidae
WMegalograptidae
WMixopteridae
WMoselopteridae
WMycteroptidae
WOnychopterellidae
WPalaeontinidae
WParastylonuridae
WPhillipsiidae
WPlesiosiro
WPleurojulidae
WProetidae
WRhenopteridae
WStenophlebiidae
WStrabopidae
WStrobilopteridae
WStylonuridae
WTarsophlebiidae