| Perithecia with simple ostioles. | ||
| Paraphyses disappearing early, or wanting. | ||
| Spores simple, ellipsoid | 1. | Verrucaria Web. |
| Spores simple, elongate vermiform | 2. | Sarcopyrenia Nyl. |
| Spores simple, numerous in the ascus | 3. | *Trimmatothele Norm. |
| Spores 1-3-septate | 4. | Thelidium Massal. |
| Spores muriform (with transverse and longitudinal divisions). | ||
| Without hymenial gonidia | 5. | Polyblastia Massal. |
| With hymenial gonidia | 6. | Staurothele Norm. |
| Paraphyses present. | ||
| Spores simple. | ||
| Without hymenial gonidia | 7. | Thrombium Wallr. |
| With hymenial gonidia | 8. | *Thelenidia Nyl. |
| Spores 3-septate, broadly ellipsoid | 9. | *Geisleria Nitschke. |
| Spores acicular, many-septate | 10. | Gongylia Koerb. |
| Spores muriform | 11. | Microglaena Lönnr. |
| Perithecia with a wide ring round the ostiole. | ||
| Spores muriform; paraphyses unbranched | 12. | *Aspidothelium Wain. |
| Spores elongate, many-septate; paraphyses branched | 13. | *Aspidopyrenium Wain. |
IV. Dermatocarpaceae
In this family there is a much more advanced thalline development—generally squamulose or with some degree of foliose structure, though in the genus Endocarpon, some of the species are little more than crustaceous. The gonidia are bright-green Protococcaceae (according to Chodat, Coccobotrys in Dermatocarpon). In Endocarpon they appear in the hymenium.
The least developed in structure is Normandina: the thallus of the single species consists of delicate shell-like squamules which are non-corticate above and below. In the other genera there is a cortex of plectenchyma.
The perithecia are almost wholly immersed, and open above by a straight ostiole. The fructification of Dacampia is considered by some lichenologists to be only a parasite on the white thickish squamulose thallus with which it is associated.
| Hymenial gonidia present. | ||
| Spores muriform | 1. | Endocarpon Hedw. |
| Hymenial gonidia absent. | ||
| Thallus non-corticate | 2. | Normandina Wain. |
| Thallus corticate. | ||
| Spores simple, colourless | 3. | Dermatocarpon Eschw. |
| Spores simple, brown | 4. | *Anapyrenium Müll.-Arg. |
| Spores elongate-septate, colourless | 5. | *Placidiopsis Beltr. |
| Spores elongate-septate, brown | 6. | *Heterocarpon Müll.-Arg. |
| Spores muriform, colourless | 7. | *Psoroglaena Müll.-Arg. |
| Spores muriform, brown | 8. | Dacampia Massal. |
V. Pyrenothamniaceae
Thallus more or less fruticose and corticate on both surfaces. Algal cells Protococcaceae.
Only two genera are included in this family: Nylanderiella with one species from New Zealand, with a small laciniate thallus up to 15 mm. in height, partly upright, partly decumbent, and attached to the substratum by basal rhizinae; the other small genus, Pyrenothamnia, belongs to N. America; the thallus has a short rounded stalk which expands above to an irregular frond. The perithecia are immersed in the fronds.
| Spores colourless, 1-septate | 1. | *Nylanderiella Hue[1039]. |
| Spores brown, muriform | 2. | *Pyrenothamnia Tuckerm. |