There is abundant detritus formation in this family; the outer layers of the cortex are continually being sloughed, the dead tissues lying on the upper surface as a dark gelatinous layer, continuous or in small patches. On the under surface the cast-off cortex gathers into a loose confused mass of dead tissues. Asci 8-spored. Spores mostly simple (disc gyrose) 1. Gyrophora Ach. Spores 1-septate 2. *Dermatiscum Nyl. Asci 1-2-spored. Spores muriform 3. Umbilicaria Hoffm. XXXV. _ACAROSPORACEAE_ Thallus foliose, squamulose or crustaceous, sometimes scarcely developed. Algal cells Protococcaceae. Into this family Zahlbruckner has gathered the genera in which the asci are many-spored, as he considers that a character of great importance in determining relationship, but he has in doing so overlooked other very great differences. The fruit-bodies are round and completely enclosed in a thalline wall in _Thelocarpon_, which has however no perithecial wall. They have a proper margin only (lecideine) in _Biatorella_, and a thalline margin (lecanorine) in the remaining genera. In _Acarospora_ the apothecia are sunk in the thallus. Stirton’s genus _Cryptothecia_[1053] is allied to _Thelocarpon_ in the fruit-formation, but the basal thallus is well developed and the spores are few in number and variously divided. Thallus none. Apothecia (or perithecia) in thalline warts 1. Thelocarpon Nyl. Thallus crustaceous. Apothecia lecideine; spores simple 2. Biatorella Th. Fr. Apothecia lecanorine; spores septate 3. *Maronea Massal. Thallus of small squamules 4. Acarospora Massal. Thallus almost foliose, attached centrally 5. *Glypholecia Nyl. XXXVI. _EPHEBACEAE_ A family of very simple structure either filamentous, foliose or crustaceous. The algal cells which give a dark colour to the thallus are _Stigonema_ or _Scytonema_, members of the blue-green Myxophyceae, and consist of minute simple or branched filaments—single cell-rows in _Scytonema_, compound in _Stigonema_. In some of the genera the lichen hyphae travel within the gelatinous sheath of the filaments, both algae and hyphae increasing by apical growth so that filaments many times the length of the alga are formed as in _Ephebe_. In others the filaments scarcely increase beyond the normal size of the alga as in _Thermutis (Gonionema)_; or the gelatinous algal cells may be distributed in a stratum of hyphae. The apothecia are minute and almost closed; they may be embedded in swellings of the thallus, or are more or less superficial. The spores are rather small, colourless and simple or 1-septate.