Detailed study of the holotype and topotypes of the type species of Trochophyllum Milne-Edwards and Haime reveals that this genus has a unique internal morphology most similar to Neaxon Kullman. Although the systematic relationships of small, aulate solitary corals remain dubious, Trochophyllum is referred provisionally to the family Petraiidae de Koninck. The genus is represented by the type species, T. verneuilanum Milne-Edwards and Haime, and the informal taxon T. sp. 1, which are known only from Tournaisian (early Osagean) strata in Kentucky and Indiana, USA. Previously published records of Trochophyllum outside the type locality of its type species are either invalid or unconfirmable on present published information Trochophyllum is distinguished by a highly variable aulos that is typically of the stereotheca-type, filled with stereoplasm at maturity; axial tabulae absent or not preserved at maturity;
cardinal septum shortened in the calice; and minor septa developed only as foundations.

Key words: corals, Rugosa. Carboniferous, systematics.