Dixonia was established for Discoidea minima, which differs from Discoides in having a fifth gonopore, a more rounded profile and a somewhat smaller periproct. Although in size and general appearance it resembles Discoides, its apical disc is identical in structure to that of Camerogalerus, as is its ambulacral plate compounding. Like Camerogalerus it has sharp, blade-like internal partitions. All three characters point to closer relationship with Camerogalerus cylindricus than with Discoides subuculus.
Smith, A. B. & Wright, C. W. 1999. British Cretaceous Echinoids. Part 5, Holectypoida, Echinoneoida. Palaeontographical Society Monographs, 343-390, pls 115-129.