Five monospecific genera (Hexactinellida, Hexactinosida), all based upon original specimens lacking loose spicules, are generally regarded as too inadequately known for family placement. They are here included in Hexactinosida as incertae sedis. Cyathella lutea Schmidt, is a distinctive and well-characterized West Indian species (specimens known), but its dictyonal construction has not yet been assignable to euretoid, aulocalycoid, or some other as yet undefined pattern. Deanea virgultosa Bowerbank, is based upon two small, eroded West Indian (?) fragments (specimens known) with rotulate dictyonal frameworks, and may thus have affinity to Dactylocalycidae. Diaretula cornu Schmidt, is based upon a single West Indian specimen (specimen location unknown) with only body form as a questionably distinctive character. Fieldingia lagettoides Kent, based upon a single specimen from off Portugal (specimen known), has many distinctive features including external multi-lamellar crust and internal spherical siliceous bodies, but the basic pattern of dictyonal construction remains undetermined. Hyalocaulus simplex Marshall Meyer, is based upon a severely eroded dictyonal framework with no distinctive features noted in its original description. The specimen was probably destroyed and its identity will probably remain unresolved.
KeywordsHexactinellida Hexactinosida incertae sedis Cyathella Deanea Diaretula Fieldingia Hyalocaulus
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