Subclass CALCARONEA Bidder, 1898

“ Calcarea with diactines and/or sagittal triactines and tetractines, rarely also with regular spicules. In addition to the free spicules, there can be a non-spicular basal calcareous skeleton in which basal spicules are cemented together or completely embedded in an enveloping calcareous cement. In ontogeny, the first spicules to be produced are diactines in the settled larva. Choanocytes are apinucleate and the basal system of the flagellum is adjacent to the apical region of the nucleus” (Borojević et al. 2000).