Series I. Perithecium simple not divided.
a. With _Pleurococcus_ or _Palmella_ gonidia. Moriolaceae,
Verrucariaceae, Pyrenothamnaceae.
b. With _Chroolepus_ gonidia. Pyrenulaceae, Paratheliaceae.
c. With _Phyllactidium_ or _Cephaleurus_ gonidia. Strigulaceae.
d. With _Nostoc_ or _Scytonema_ gonidia. Pyrenidiaceae.
Series II. Perithecia divided or imperfectly divided by cross-walls.
Mycoporaceae with _Palmella_ or _Chroolepus_ gonidia.