WAntigonaria
WAntroposthiidae
WAscopariidae
WConvoluta convoluta
WMeara (genus)
WNemertodermatida
WNemertodermatidae
WNeochildia fusca
WProporidae
WWaminoa
WXenacoelomorpha
WXenoturbella churro
WXenoturbella hollandorum
WXenoturbella japonica
WXenoturbella monstrosa
WXenoturbella profunda