Both genera have a wide distribution over the globe, more especially in maritime regions.
| Thallus foliose | 1. | Xanthoria Th. Fr. |
| Thallus fruticose | 2. | Teloschistes Norm. |
L. Buelliaceae
A family of crustaceous lichens distinguished by the brown two-celled spores. Algal cells Protococcaceae. Zahlbruckner has included here Buellia and Rinodina; the former with a distinctly lecideine fruit and with thinly septate spores; the latter lecanorine and with spores of the polarilocular type, with a very wide central septum pierced in most of the species by a canal which may or may not traverse the middle lamella of the wall. Rinodina is closely allied to Physciaceae, while Buellia has more affinity with Lecideaceae and is near to Rhizocarpon.
Both genera are of world-wide distribution.
| Apothecia lecideine, without a thalline margin | 1. | Buellia De Not. |
| Apothecia lecanorine, with a thalline margin | 2. | Rinodina Massal. |
LI. Physciaceae
Thallus foliose or partly fruticose, and generally attached by rhizinae. Algal cells Protococcaceae. The spores resemble those of Rinodina, dark-coloured with a thick septum and reduced cell-lumina. As in that species there may be a second septum in each cell, giving a 3-septate spore; but that is rare.
Pyxine, a tropical or subtropical genus, is lecanorine only in the very early stages; it soon loses the thalline margin. Anaptychia is differentiated from Physcia by the subfruticose habit, though the species are nearly all dorsiventral in structure, only a few of them being truly radiate and corticate on both surfaces. The upper cortex of Anaptychia is fibrous, but that character appears also in most species of Physcia either on the upper or the lower side. Physcia and Anaptychia are widely distributed.
| Thalline margin absent in apothecia | 1. | *Pyxine Nyl. |
| Thalline margin present in apothecia. | ||
| Thallus foliose | 2. | Physcia Schreb. |
| Thallus fruticose | 3. | Anaptychia Koerb. |