Genera and species are mostly tropical. Sclerophyton with five species is represented in Europe by a single British specimen, S. circumscriptum.
The form of the paraphyses is a distinguishing character of the genera.
| Thallus with Trentepohlia gonidia. | ||
| Paraphyses free, unbranched. | ||
| Spore cells short or almost globose. | ||
| Spores elongate, multi-septate, colourless | 1. | Glyphis Fée. |
| Spores elongate, multi-septate, brown | 2. | *Sarcographa Fée. |
| Spores muriform, brown | 3. | *Sarcographina Müll.-Arg. |
| Spore cells longer and cuboid. | ||
| Spores muriform, colourless | 4. | *Enterodictyon Müll.-Arg. |
| Paraphyses branched, interwoven above. | ||
| Spores elongate, multi-septate, colourless | 5. | Chiodecton Ach. |
| Spores elongate, multi-septate, brown | 6. | Sclerophyton Eschw. |
| Spores muriform, colourless | 7. | *Minksia Müll.-Arg. |
| Spores muriform, brown | 8. | *Enterostigma Müll.-Arg. |
| Thallus with Phycopeltis gonidia (epiphyllous). | ||
| Paraphyses free. | ||
| Spores unequally 2-celled, colourless | 9. | *Pycnographa Müll.-Arg. |
| Paraphyses branched, interwoven above. | ||
| Spores elongate, multi-septate, colourless | 10. | *Mazosia Massal. |
XXI. Dirinaceae
A small family, which is associated with and often included under Graphidaceae. The thallus is crustaceous and corticate on the upper surface, the cortex being formed of palisade hyphae. Algal cells Trentepohlia. Apothecia are rounded or with a tendency to elongation, and, in addition to a thin proper margin, possess a stout thalline margin; the hypothecium is thick and carbonaceous. There are two genera: Dirina with twelve species has a wide distribution; Dirinastrum is monotypic and occurs on maritime rocks in Australia. In both the spores are elongate-septate, differing only in colour:
| Spores colourless | 1. | Dirina Fr. |
| Spores brown | 2. | *Dirinastrum Müll.-Arg. |
XXII. Roccellaceae
The Roccellaceae differ from the preceding Dirinaceae chiefly in the fruticose thallus which is more or less characteristic of all the genera, though in Roccellographa it expands into foliose dimensions and in Roccellina is reduced to short podetia-like processes from a crustose base. The fronds—mostly long and strap-shaped—are protected in most of the genera by a cortex of compact palisade hyphae; in a few the outer hyphae are parallel with the long axis. The medulla is of parallel hyphae, either loose or compact. The algal cells are Trentepohlia.
The apothecia are lateral except in Roccellina where they occur at the tips of the short upright fronds, and only in Roccellaria is there no thalline margin. They are superficial in all of the genera except Roccellographa, in which they are immersed and almost closed, recalling the perithecia-like fruits of Chiodecton (sect. Enterographa). The spores are elongate, narrow, pluri-septate, and colourless or brownish, except in Darbishirella in which they are ovoid, 2-septate and brown.